diff --git a/arduino-ide-extension/src/browser/arduino-ide-frontend-module.ts b/arduino-ide-extension/src/browser/arduino-ide-frontend-module.ts
index bc0caaee195..2353ef8d953 100644
--- a/arduino-ide-extension/src/browser/arduino-ide-frontend-module.ts
+++ b/arduino-ide-extension/src/browser/arduino-ide-frontend-module.ts
@@ -204,6 +204,9 @@ import { DebugConfigurationManager } from './theia/debug/debug-configuration-man
 import { DebugConfigurationManager as TheiaDebugConfigurationManager } from '@theia/debug/lib/browser/debug-configuration-manager';
 import { SearchInWorkspaceFactory as TheiaSearchInWorkspaceFactory } from '@theia/search-in-workspace/lib/browser/search-in-workspace-factory';
 import { SearchInWorkspaceFactory } from './theia/search-in-workspace/search-in-workspace-factory';
+import { SearchInWorkspaceResultTreeWidget as TheiaSearchInWorkspaceResultTreeWidget } from '@theia/search-in-workspace/lib/browser/search-in-workspace-result-tree-widget';
+import { SearchInWorkspaceResultTreeWidget } from './theia/search-in-workspace/search-in-workspace-result-tree-widget';
+import { createTreeContainer } from '@theia/core/lib/browser/tree/tree-container';
 import { MonacoEditorProvider } from './theia/monaco/monaco-editor-provider';
 import {
   MonacoEditorFactory,
@@ -610,6 +613,20 @@ export default new ContainerModule((bind, unbind, isBound, rebind) => {
     .to(SearchInWorkspaceFactory)
     .inSingletonScope();
 
+  // Fix regex replace escape sequences (issue #2803)
+  // The widget uses a factory pattern, so we need to rebind with a custom factory
+  rebind(TheiaSearchInWorkspaceResultTreeWidget).toDynamicValue((ctx) => {
+    const child = createTreeContainer(ctx.container, {
+      widget: SearchInWorkspaceResultTreeWidget,
+      props: {
+        contextMenuPath: ['search-in-workspace-result-tree-context-menu'],
+        multiSelect: true,
+        globalSelection: true,
+      },
+    });
+    return child.get(SearchInWorkspaceResultTreeWidget);
+  });
+
   // Show a disconnected status bar, when the daemon is not available
   bind(ApplicationConnectionStatusContribution).toSelf().inSingletonScope();
   rebind(TheiaApplicationConnectionStatusContribution).toService(
diff --git a/arduino-ide-extension/src/browser/theia/search-in-workspace/search-in-workspace-result-tree-widget.ts b/arduino-ide-extension/src/browser/theia/search-in-workspace/search-in-workspace-result-tree-widget.ts
new file mode 100644
index 00000000000..ec84ae8c47a
--- /dev/null
+++ b/arduino-ide-extension/src/browser/theia/search-in-workspace/search-in-workspace-result-tree-widget.ts
@@ -0,0 +1,66 @@
+import { injectable } from '@theia/core/shared/inversify';
+import { TreeNode } from '@theia/core/lib/browser/tree';
+import { SearchInWorkspaceResultTreeWidget as TheiaSearchInWorkspaceResultTreeWidget } from '@theia/search-in-workspace/lib/browser/search-in-workspace-result-tree-widget';
+
+/**
+ * Parses escape sequences in replacement string when regex mode is enabled.
+ * Converts \n, \t, \r, \\ to actual characters.
+ *
+ * @param replaceString The raw replacement string with escape sequences
+ * @returns The processed string with escape sequences converted to actual characters
+ */
+export function parseReplaceString(replaceString: string): string {
+  let result = '';
+  let i = 0;
+  while (i < replaceString.length) {
+    const char = replaceString[i];
+    if (char === '\\' && i + 1 < replaceString.length) {
+      const nextChar = replaceString[i + 1];
+      switch (nextChar) {
+        case 'n':
+          result += '\n';
+          i += 2;
+          continue;
+        case 't':
+          result += '\t';
+          i += 2;
+          continue;
+        case 'r':
+          result += '\r';
+          i += 2;
+          continue;
+        case '\\':
+          result += '\\';
+          i += 2;
+          continue;
+        default:
+          result += char;
+          i++;
+          continue;
+      }
+    }
+    result += char;
+    i++;
+  }
+  return result;
+}
+
+@injectable()
+export class SearchInWorkspaceResultTreeWidget extends TheiaSearchInWorkspaceResultTreeWidget {
+  /**
+   * Override replaceResult to parse escape sequences in replacement text
+   * when regex mode is enabled. Fixes GitHub issue #2803.
+   *
+   * https://github.com/arduino/arduino-ide/issues/2803
+   */
+  protected override async replaceResult(
+    node: TreeNode,
+    replaceOne: boolean,
+    replacementText: string
+  ): Promise<void> {
+    const processedText = this.searchOptions?.useRegExp
+      ? parseReplaceString(replacementText)
+      : replacementText;
+    return super.replaceResult(node, replaceOne, processedText);
+  }
+}
diff --git a/arduino-ide-extension/src/test/browser/parse-replace-string.test.ts b/arduino-ide-extension/src/test/browser/parse-replace-string.test.ts
new file mode 100644
index 00000000000..66fabd08160
--- /dev/null
+++ b/arduino-ide-extension/src/test/browser/parse-replace-string.test.ts
@@ -0,0 +1,62 @@
+import { expect } from 'chai';
+import { parseReplaceString } from '../../browser/theia/search-in-workspace/search-in-workspace-result-tree-widget';
+
+describe('parseReplaceString', () => {
+  it('should convert \\n to newline', () => {
+    expect(parseReplaceString('\\n')).to.equal('\n');
+  });
+
+  it('should convert \\t to tab', () => {
+    expect(parseReplaceString('\\t')).to.equal('\t');
+  });
+
+  it('should convert \\r to carriage return', () => {
+    expect(parseReplaceString('\\r')).to.equal('\r');
+  });
+
+  it('should convert \\\\ to single backslash', () => {
+    expect(parseReplaceString('\\\\')).to.equal('\\');
+  });
+
+  it('should handle \\\\n as literal backslash followed by n', () => {
+    expect(parseReplaceString('\\\\n')).to.equal('\\n');
+  });
+
+  it('should handle mixed content', () => {
+    expect(parseReplaceString('hello\\nworld')).to.equal('hello\nworld');
+  });
+
+  it('should handle multiple sequences', () => {
+    expect(parseReplaceString('\\n\\n')).to.equal('\n\n');
+  });
+
+  it('should return unchanged string without escape sequences', () => {
+    expect(parseReplaceString('hello')).to.equal('hello');
+  });
+
+  it('should handle empty string', () => {
+    expect(parseReplaceString('')).to.equal('');
+  });
+
+  it('should keep unknown escape sequences as backslash followed by char', () => {
+    expect(parseReplaceString('\\x')).to.equal('\\x');
+  });
+
+  it('should handle trailing backslash', () => {
+    expect(parseReplaceString('hello\\')).to.equal('hello\\');
+  });
+
+  it('should handle complex mixed content', () => {
+    expect(parseReplaceString('line1\\nline2\\ttabbed\\r\\nwindows')).to.equal(
+      'line1\nline2\ttabbed\r\nwindows'
+    );
+  });
+
+  it('should handle multiple escaped backslashes', () => {
+    expect(parseReplaceString('\\\\\\\\')).to.equal('\\\\');
+  });
+
+  it('should preserve text around escape sequences', () => {
+    expect(parseReplaceString('prefix\\nsuffix')).to.equal('prefix\nsuffix');
+  });
+});