diff --git a/lib/irb/command/reload.rb b/lib/irb/command/reload.rb
new file mode 100644
index 000000000..9b0193282
--- /dev/null
+++ b/lib/irb/command/reload.rb
@@ -0,0 +1,69 @@
+# frozen_string_literal: true
+
+module IRB
+  # :stopdoc:
+
+  module Command
+    class BoxReload < Base
+      category "IRB"
+      description "[Experimental] Reload files that were loaded via require in IRB session (requires Ruby::Box)."
+
+      help_message <<~HELP
+        Usage: box_reload
+
+        Reloads all Ruby files that were loaded via `require` or `require_relative`
+        during the current IRB session. This allows you to pick up changes made to
+        source files without restarting IRB.
+
+        Setup:
+          1. Start Ruby with RUBY_BOX=1 environment variable
+          2. Set IRB.conf[:RELOADABLE_REQUIRE] = true in your .irbrc
+
+        Example:
+          # In .irbrc:
+          IRB.conf[:RELOADABLE_REQUIRE] = true
+
+          # In IRB session:
+          require 'my_lib'  # loaded and tracked
+          # ... edit my_lib.rb ...
+          box_reload         # reloads the file
+
+        Note: This feature is experimental and requires Ruby::Box (Ruby 4.0+).
+        Native extensions (.so/.bundle) cannot be reloaded.
+      HELP
+
+      def execute(_arg)
+        unless reloadable_require_available?
+          warn "box_reload requires IRB.conf[:RELOADABLE_REQUIRE] = true and Ruby::Box (Ruby 4.0+) with RUBY_BOX=1 environment variable."
+          return
+        end
+
+        ReloadableRequire.collect_autoloaded_files
+        files = ReloadableRequire.reloadable_files
+        if files.empty?
+          puts "No files to reload. Use require to load files first."
+          return
+        end
+
+        files.each { |path| reload_file(path) }
+      end
+
+      private
+
+      def reloadable_require_available?
+        IRB.conf[:RELOADABLE_REQUIRE] && defined?(Ruby::Box) && Ruby::Box.enabled?
+      end
+
+      def reload_file(path)
+        load path
+        puts "Reloaded: #{path}"
+      rescue LoadError => e
+        warn "Failed to reload #{path}: #{e.message}"
+      rescue SyntaxError => e
+        warn "Syntax error in #{path}: #{e.message}"
+      end
+    end
+  end
+
+  # :startdoc:
+end
diff --git a/lib/irb/default_commands.rb b/lib/irb/default_commands.rb
index 9820a1f30..8138f8232 100644
--- a/lib/irb/default_commands.rb
+++ b/lib/irb/default_commands.rb
@@ -26,6 +26,7 @@
 require_relative "command/measure"
 require_relative "command/next"
 require_relative "command/pushws"
+require_relative "command/reload"
 require_relative "command/show_doc"
 require_relative "command/show_source"
 require_relative "command/step"
@@ -252,6 +253,7 @@ def load_command(command)
 
     register(:cd, Command::CD)
     register(:copy, Command::Copy)
+    register(:box_reload, Command::BoxReload)
   end
 
   ExtendCommand = Command
diff --git a/lib/irb/init.rb b/lib/irb/init.rb
index 365f445da..750651b49 100644
--- a/lib/irb/init.rb
+++ b/lib/irb/init.rb
@@ -197,6 +197,8 @@ def IRB.init_config(ap_path)
     }
 
     @CONF[:COPY_COMMAND] = ENV.fetch("IRB_COPY_COMMAND", nil)
+
+    @CONF[:RELOADABLE_REQUIRE] = false
   end
 
   def IRB.set_measure_callback(type = nil, arg = nil, &block)
diff --git a/lib/irb/reloadable_require.rb b/lib/irb/reloadable_require.rb
new file mode 100644
index 000000000..a40a40477
--- /dev/null
+++ b/lib/irb/reloadable_require.rb
@@ -0,0 +1,93 @@
+# frozen_string_literal: true
+
+if !defined?(Ruby::Box) || !Ruby::Box.enabled?
+  raise "ReloadableRequire requires Ruby::Box to be enabled"
+end
+
+require 'set'
+
+module IRB
+  # Provides reload-aware require functionality for IRB.
+  #
+  # This feature is experimental and requires Ruby::Box (Ruby 4.0+).
+  #
+  # Limitations:
+  # - Native extensions cannot be reloaded (load doesn't support them)
+  # - Constant redefinition warnings will appear on reload (uses load internally)
+
+  module ReloadableRequire
+    @reloadable_files = Set.new
+    @autoload_features = {}
+
+    class << self
+      attr_reader :reloadable_files, :autoload_features
+
+      def track_and_load_files(source, current_box)
+        before = source.dup
+        result = yield
+        new_files = source - before
+
+        return result if new_files.empty?
+
+        ruby_files, native_extensions = new_files.partition { |path| path.end_with?('.rb') }
+
+        native_extensions.each { |path| current_box.require(path) }
+
+        @reloadable_files.merge(ruby_files)
+
+        main_loaded_features = current_box.eval('$LOADED_FEATURES')
+        main_loaded_features.concat(ruby_files - main_loaded_features)
+        ruby_files.each { |path| current_box.load(path) }
+
+        result
+      end
+
+      def collect_autoloaded_files
+        @autoload_features.each_value do |feature|
+          resolved = $LOAD_PATH.resolve_feature_path(feature) rescue nil
+          next unless resolved && resolved.first == :rb
+          path = resolved[1]
+          @reloadable_files << path if $LOADED_FEATURES.include?(path)
+        end
+      end
+    end
+
+    private
+
+    def reloadable_require_internal(feature, caller_box)
+      box = Ruby::Box.new
+      box.eval("$LOAD_PATH.concat(#{caller_box.eval('$LOAD_PATH')})")
+      box.eval("$LOADED_FEATURES.concat(#{caller_box.eval('$LOADED_FEATURES')})")
+
+      ReloadableRequire.track_and_load_files(box.eval('$LOADED_FEATURES'), caller_box) { box.require(feature) }
+    end
+
+    def require(feature)
+      caller_loc = caller_locations(1, 1).first
+      return super unless caller_loc.path.end_with?("(irb)")
+
+      reloadable_require_internal(feature, Ruby::Box.main)
+    rescue LoadError
+      super
+    end
+
+    def require_relative(feature)
+      caller_loc = caller_locations(1, 1).first
+      current_box = Ruby::Box.main
+
+      unless caller_loc.path.end_with?("(irb)")
+        file_path = caller_loc.absolute_path || caller_loc.path
+        return current_box.eval("eval('Kernel.require_relative(#{feature.dump})', nil, #{file_path.dump}, #{caller_loc.lineno})")
+      end
+
+      reloadable_require_internal(File.expand_path(feature, Dir.pwd), current_box)
+    rescue LoadError
+      super
+    end
+
+    def autoload(const, feature)
+      ReloadableRequire.autoload_features[const.to_s] = feature
+      Ruby::Box.main.eval("Kernel.autoload(:#{const}, #{feature.dump})")
+    end
+  end
+end
diff --git a/lib/irb/workspace.rb b/lib/irb/workspace.rb
index 9fef8f86a..dee974ec5 100644
--- a/lib/irb/workspace.rb
+++ b/lib/irb/workspace.rb
@@ -5,6 +5,7 @@
 #
 
 require_relative "helper_method"
+require_relative "reloadable_require" if defined?(Ruby::Box) && Ruby::Box.enabled?
 
 IRB::TOPLEVEL_BINDING = binding
 module IRB # :nodoc:
@@ -103,6 +104,10 @@ def load_helper_methods_to_main
       ancestors = class<<main;ancestors;end
       main.extend ExtendCommandBundle if !ancestors.include?(ExtendCommandBundle)
       main.extend HelpersContainer if !ancestors.include?(HelpersContainer)
+
+      if IRB.conf[:RELOADABLE_REQUIRE] && defined?(ReloadableRequire) && !ancestors.include?(ReloadableRequire)
+        main.extend ReloadableRequire
+      end
     end
 
     # Evaluate the given +statements+ within the  context of this workspace.
diff --git a/test/irb/test_reloadable_require.rb b/test/irb/test_reloadable_require.rb
new file mode 100644
index 000000000..420e58203
--- /dev/null
+++ b/test/irb/test_reloadable_require.rb
@@ -0,0 +1,365 @@
+# frozen_string_literal: true
+
+require "tempfile"
+require "fileutils"
+
+require_relative "helper"
+
+module TestIRB
+  class ReloadableRequireIntegrationTest < IntegrationTestCase
+    def setup
+      super
+
+      omit "ReloadableRequire requires Ruby::Box" if !defined?(Ruby::Box) || !Ruby::Box.enabled?
+
+      @envs["RUBY_BOX"] = "1"
+
+      setup_lib_files
+
+      write_rc <<~RUBY
+        IRB.conf[:RELOADABLE_REQUIRE] = true
+        $LOAD_PATH.unshift('#{@lib_dir}')
+      RUBY
+    end
+
+    def teardown
+      super
+      FileUtils.rm_rf(@lib_dir) if @lib_dir
+      @pwd_files&.each { |f| File.delete(f) if File.exist?(f) }
+    end
+
+    def test_require_enables_reload
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      output = run_ruby_file do
+        type "require 'nested_a'"
+        type "NESTED_A_VALUE"
+        type "NESTED_B_VALUE"
+        type "box_reload"
+        type "exit!"
+      end
+
+      assert_include output, "=> \"from_a\""
+      assert_include output, "=> \"from_b\""
+      assert_include output, "Reloaded: #{@nested_a_path}"
+      assert_include output, "Reloaded: #{@nested_b_path}"
+    end
+
+    def test_require_relative_from_irb_prompt_enables_reload
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      output = run_ruby_file do
+        type "require_relative 'require_relative_lib'"
+        type "REQUIRE_RELATIVE_LIB_VALUE"
+        type "REQUIRE_RELATIVE_DEP"
+        type "box_reload"
+        type "exit!"
+      end
+
+      assert_include output, "=> 42"
+      assert_include output, "=> \"dep\""
+      assert_include output, "Reloaded: #{@require_relative_lib_path}"
+      assert_include output, "Reloaded: #{@require_relative_dep_path}"
+    end
+
+    def test_require_with_nested_require_relative_enables_reload
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      output = run_ruby_file do
+        type "require '#{@relative_nested_a_path}'"
+        type "RELATIVE_NESTED_A"
+        type "RELATIVE_NESTED_B"
+        type "box_reload"
+        type "exit!"
+      end
+
+      assert_include output, "=> \"from_a\""
+      assert_include output, "=> \"from_b\""
+      assert_include output, "Reloaded: #{@relative_nested_a_path}"
+      assert_include output, "Reloaded: #{@relative_nested_b_path}"
+    end
+
+    def test_autoload_enables_reload
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      output = run_ruby_file do
+        type "autoload :AutoloadMain, 'autoload_main'"
+        type "AutoloadMain::VALUE"
+        type "AUTOLOAD_DEP_VALUE"
+        type "box_reload"
+        type "exit!"
+      end
+
+      assert_include output, "=> \"main\""
+      assert_include output, "=> \"dependency\""
+      assert_include output, "Reloaded: #{@autoload_main_path}"
+      assert_include output, "Reloaded: #{@autoload_dep_path}"
+    end
+
+    def test_reload_without_any_loaded_files
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      output = run_ruby_file do
+        type "box_reload"
+        type "exit!"
+      end
+
+      assert_include output, "No files to reload"
+    end
+
+    def test_reload_reflects_file_changes
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      output = run_ruby_file do
+        type "require '#{@changeable_lib_path}'"
+        type "CHANGEABLE_VALUE"
+        type "File.write('#{@changeable_lib_path}', \"CHANGEABLE_VALUE = 'modified'\\n\")"
+        type "box_reload"
+        type "CHANGEABLE_VALUE"
+        type "exit!"
+      end
+
+      assert_include output, "=> \"original\""
+      assert_include output, "Reloaded: #{@changeable_lib_path}"
+      assert_include output, "=> \"modified\""
+    end
+
+    def test_reload_command_without_reloadable_require_enabled
+      write_rc <<~'RUBY'
+        IRB.conf[:RELOADABLE_REQUIRE] = false
+      RUBY
+
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      output = run_ruby_file do
+        type "box_reload"
+        type "exit!"
+      end
+
+      assert_include output, "requires IRB.conf[:RELOADABLE_REQUIRE] = true"
+    end
+
+    def test_require_updates_loaded_features
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      output = run_ruby_file do
+        type "require 'nested_a'"
+        type "$LOADED_FEATURES.include?('#{@nested_a_path}')"
+        type "$LOADED_FEATURES.include?('#{@nested_b_path}')"
+        type "exit!"
+      end
+
+      # Both files should be in $LOADED_FEATURES
+      assert_equal 2, output.scan("=> true").count
+    end
+
+    def test_autoload_updates_loaded_features
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      output = run_ruby_file do
+        type "autoload :AutoloadMain, 'autoload_main'"
+        type "AutoloadMain"
+        type "$LOADED_FEATURES.include?('#{@autoload_main_path}')"
+        type "$LOADED_FEATURES.include?('#{@autoload_dep_path}')"
+        type "exit!"
+      end
+
+      # Both files should be in $LOADED_FEATURES
+      assert_equal 2, output.scan("=> true").count
+    end
+
+    def test_reload_preserves_loaded_features
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      output = run_ruby_file do
+        type "require 'nested_a'"
+        type "$LOADED_FEATURES.include?('#{@nested_a_path}')"
+        type "box_reload"
+        type "$LOADED_FEATURES.include?('#{@nested_a_path}')"
+        type "exit!"
+      end
+
+      # Both checks should return true (before and after reload)
+      assert_equal 2, output.scan("=> true").count
+    end
+
+    def test_require_native_extension
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      output = run_ruby_file do
+        type "require 'etc'"
+        type "Etc.getlogin"
+        type "exit!"
+      end
+
+      assert_include output, "=> true"
+    end
+
+    def test_require_does_not_modify_load_path
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      output = run_ruby_file do
+        type "load_path_before = $LOAD_PATH.dup"
+        type "require 'nested_a'"
+        type "$LOAD_PATH == load_path_before"
+        type "exit!"
+      end
+
+      assert_include output, "=> true"
+    end
+
+    private
+
+    def setup_lib_files
+      @lib_dir = Dir.mktmpdir
+      @pwd_files = []
+
+      # Nested require files (primary test files)
+      @nested_b_path = create_lib_file("nested_b.rb", "NESTED_B_VALUE = 'from_b'\n")
+      @nested_a_path = create_lib_file("nested_a.rb", "require 'nested_b'\nNESTED_A_VALUE = 'from_a'\n")
+
+      # Nested require_relative files (for testing require that internally uses require_relative)
+      @relative_nested_b_path = create_lib_file("relative_nested_b.rb", "RELATIVE_NESTED_B = 'from_b'\n")
+      @relative_nested_a_path = create_lib_file(
+        "relative_nested_a.rb",
+        "require_relative 'relative_nested_b'\nRELATIVE_NESTED_A = 'from_a'\n"
+      )
+
+      # Files in Dir.pwd for require_relative from IRB prompt (with nested dependency)
+      @require_relative_dep_path = create_pwd_file("require_relative_dep.rb", "REQUIRE_RELATIVE_DEP = 'dep'\n")
+      @require_relative_lib_path = create_pwd_file(
+        "require_relative_lib.rb",
+        "require_relative 'require_relative_dep'\nREQUIRE_RELATIVE_LIB_VALUE = 42\n"
+      )
+
+      # Autoload files with nested require
+      @autoload_dep_path = create_lib_file("autoload_dep.rb", "AUTOLOAD_DEP_VALUE = 'dependency'\n")
+      @autoload_main_path = create_lib_file(
+        "autoload_main.rb",
+        "require 'autoload_dep'\nmodule AutoloadMain; VALUE = 'main'; end\n"
+      )
+
+      # Changeable file (for testing reload reflects changes)
+      @changeable_lib_path = create_lib_file("changeable.rb", "CHANGEABLE_VALUE = 'original'\n")
+    end
+
+    def create_lib_file(name, content)
+      path = File.join(@lib_dir, name)
+      File.write(path, content)
+      File.realpath(path)
+    end
+
+    def create_pwd_file(name, content)
+      path = File.join(Dir.pwd, name)
+      File.write(path, content)
+      @pwd_files << path
+      File.realpath(path)
+    end
+  end
+
+  class BoxReloadCommandTest < TestCase
+    def setup
+      super
+      omit "BoxReload requires Ruby::Box" if !defined?(Ruby::Box) || !Ruby::Box.enabled?
+
+      @tmpdir = Dir.mktmpdir
+      @valid_file = File.join(@tmpdir, "valid.rb")
+      File.write(@valid_file, "VALID = true\n")
+      @valid_file = File.realpath(@valid_file)
+
+      require "irb"
+      require "irb/command/reload"
+      IRB.setup(__FILE__, argv: [])
+      @original_reloadable = IRB.conf[:RELOADABLE_REQUIRE]
+      IRB.conf[:RELOADABLE_REQUIRE] = true
+
+      @saved_files = IRB::ReloadableRequire.reloadable_files.dup
+      IRB::ReloadableRequire.reloadable_files.clear
+    end
+
+    def teardown
+      super
+      FileUtils.rm_rf(@tmpdir) if @tmpdir
+      if defined?(IRB::ReloadableRequire) && @saved_files
+        IRB.conf[:RELOADABLE_REQUIRE] = @original_reloadable
+        IRB::ReloadableRequire.reloadable_files.replace(@saved_files)
+      end
+    end
+
+    def test_reload_file_preserves_loaded_features_on_syntax_error
+      $LOADED_FEATURES << @valid_file
+
+      File.write(@valid_file, "def broken(")
+
+      cmd = IRB::Command::BoxReload.new(nil)
+      IRB::ReloadableRequire.reloadable_files << @valid_file
+      cmd.execute(nil)
+
+      assert_equal true, $LOADED_FEATURES.include?(@valid_file)
+    ensure
+      $LOADED_FEATURES.delete(@valid_file)
+    end
+
+    def test_reload_file_preserves_loaded_features_on_load_error
+      missing_file = File.join(@tmpdir, "missing.rb")
+      $LOADED_FEATURES << missing_file
+
+      cmd = IRB::Command::BoxReload.new(nil)
+      IRB::ReloadableRequire.reloadable_files << missing_file
+      cmd.execute(nil)
+
+      assert_equal true, $LOADED_FEATURES.include?(missing_file)
+    ensure
+      $LOADED_FEATURES.delete(missing_file)
+    end
+  end
+
+  class ReloadableRequireDisabledTest < IntegrationTestCase
+    def setup
+      super
+
+      omit "This test is for Ruby::Box disabled environment" if defined?(Ruby::Box) && Ruby::Box.enabled?
+    end
+
+    def test_reload_command_shows_error_without_ruby_box
+      write_rc <<~'RUBY'
+        IRB.conf[:RELOADABLE_REQUIRE] = true
+      RUBY
+
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      output = run_ruby_file do
+        type "box_reload"
+        type "exit!"
+      end
+
+      assert_include output, "requires IRB.conf[:RELOADABLE_REQUIRE] = true and Ruby::Box"
+    end
+  end
+end