diff --git a/docs/keybindings.md b/docs/keybindings.md
index 919df3b..4da2476 100644
--- a/docs/keybindings.md
+++ b/docs/keybindings.md
@@ -192,6 +192,7 @@ Preview panel (panel 5).
 | `B` | Toggle blame |
 | `y/Ctrl+C` | Copy selection |
 | `Y` | Copy GitHub permalink |
+| `O` | Open file on GitHub |
 | `Esc` | Clear selection |
 
 Navigation keys (j/k/g/G/PgDn/PgUp) scroll content. Click+drag to select text, double-click to select a word.
diff --git a/internal/keybindings/keybindings.json b/internal/keybindings/keybindings.json
index 6c9e704..cb57f7c 100644
--- a/internal/keybindings/keybindings.json
+++ b/internal/keybindings/keybindings.json
@@ -168,6 +168,7 @@
         { "key": "B", "action": "Toggle blame" },
         { "key": "y/Ctrl+C", "action": "Copy selection" },
         { "key": "Y", "action": "Copy GitHub permalink" },
+        { "key": "O", "action": "Open file on GitHub" },
         { "key": "Esc", "action": "Clear selection" }
       ],
       "note": "Navigation keys (j/k/g/G/PgDn/PgUp) scroll content. Click+drag to select text, double-click to select a word."
diff --git a/internal/panels/preview/permalink.go b/internal/panels/preview/permalink.go
index 656a3b7..175589b 100644
--- a/internal/panels/preview/permalink.go
+++ b/internal/panels/preview/permalink.go
@@ -112,3 +112,41 @@ func (p *Preview) copyPermalink() (panels.Panel, tea.Cmd) {
 		return notify.ShowToastMsg{Message: "Copied GitHub permalink", Level: notify.Info}
 	}
 }
+
+// openOnGitHub builds a github.com permalink for the current file and line
+// (or selected range) and opens it in the default browser. It is a no-op with
+// a clear message when the preview is not showing an on-disk file or when the
+// repository has no github remote.
+func (p *Preview) openOnGitHub() (panels.Panel, tea.Cmd) {
+	if p.ghMode || p.filePath == "" {
+		return p, nil
+	}
+	path := p.filePath
+	gc := p.gitClient
+	startLine, endLine := p.permalinkLineRange()
+	return p, func() tea.Msg {
+		ctx := context.Background()
+		if gc == nil {
+			return notify.ShowToastMsg{Message: "No git repository", Level: notify.Warn}
+		}
+		root, err := gc.RepoRoot(ctx)
+		if err != nil || root == "" {
+			return notify.ShowToastMsg{Message: "No git repository", Level: notify.Warn}
+		}
+		relPath := path
+		if rel, err := filepath.Rel(root, path); err == nil {
+			relPath = filepath.ToSlash(rel)
+		}
+		if strings.HasPrefix(relPath, "..") {
+			return notify.ShowToastMsg{Message: "File is outside the repository", Level: notify.Warn}
+		}
+		link := buildPermalink(gitRemoteURL(ctx, root), gitHeadSHA(ctx, root), relPath, startLine, endLine)
+		if link == "" {
+			return notify.ShowToastMsg{Message: "No github remote to open", Level: notify.Warn}
+		}
+		if err := panels.OpenInBrowser(ctx, link); err != nil {
+			return notify.ShowToastMsg{Message: "Open failed: " + err.Error(), Level: notify.Error}
+		}
+		return notify.ShowToastMsg{Message: "Opened file on GitHub", Level: notify.Info}
+	}
+}
diff --git a/internal/panels/preview/permalink_test.go b/internal/panels/preview/permalink_test.go
index 08dcc8a..b7e88c6 100644
--- a/internal/panels/preview/permalink_test.go
+++ b/internal/panels/preview/permalink_test.go
@@ -121,3 +121,18 @@ func TestCopyPermalink_NoOpInGitHubMode(t *testing.T) {
 	_, cmd := p.copyPermalink()
 	assert.Nil(t, cmd)
 }
+
+func TestOpenOnGitHub_NoOpWhenNoFile(t *testing.T) {
+	p := newTestPreview([]string{"a"})
+	p.filePath = ""
+	_, cmd := p.openOnGitHub()
+	assert.Nil(t, cmd)
+}
+
+func TestOpenOnGitHub_NoOpInGitHubMode(t *testing.T) {
+	p := newTestPreview([]string{"a"})
+	p.filePath = "main.go"
+	p.ghMode = true
+	_, cmd := p.openOnGitHub()
+	assert.Nil(t, cmd)
+}
diff --git a/internal/panels/preview/preview.go b/internal/panels/preview/preview.go
index 9ef8dd3..7f0aa42 100644
--- a/internal/panels/preview/preview.go
+++ b/internal/panels/preview/preview.go
@@ -522,6 +522,8 @@ func (p *Preview) Update(msg tea.Msg) (panels.Panel, tea.Cmd) {
 			return p.copyFilePath()
 		case "Y":
 			return p.copyPermalink()
+		case "O":
+			return p.openOnGitHub()
 		case keyEscape, keyEsc:
 			if p.hasSelection() {
 				p.clearSelection()
@@ -723,6 +725,7 @@ func (p *Preview) KeyBindings() []panels.KeyBinding {
 		{Key: "B", Description: "Toggle blame", Action: "toggle_blame"},
 		{Key: "y/Ctrl+C", Description: "Copy selection or file path", Action: "copy_selection"},
 		{Key: "Y", Description: "Copy GitHub permalink", Action: "copy_permalink"},
+		{Key: "O", Description: "Open file on GitHub", Action: "open_on_github"},
 	}
 }
 
diff --git a/internal/panels/preview/preview_test.go b/internal/panels/preview/preview_test.go
index e2b4040..8d010b6 100644
--- a/internal/panels/preview/preview_test.go
+++ b/internal/panels/preview/preview_test.go
@@ -778,7 +778,7 @@ func TestKeyBindings(t *testing.T) {
 	bindings := p.KeyBindings()
 
 	assert.NotEmpty(t, bindings)
-	assert.Len(t, bindings, 15)
+	assert.Len(t, bindings, 16)
 
 	// Verify all expected bindings are present
 	actions := make([]string, len(bindings))
@@ -802,6 +802,7 @@ func TestKeyBindings(t *testing.T) {
 	assert.Contains(t, actions, "toggle_diff_mode")
 	assert.Contains(t, actions, "copy_selection")
 	assert.Contains(t, actions, "copy_permalink")
+	assert.Contains(t, actions, "open_on_github")
 }
 
 func TestKeysIgnoredWhenBlurred(t *testing.T) {