diff --git a/packages/cli/src/config/keyBindings.ts b/packages/cli/src/config/keyBindings.ts
index 497b359f2ef..c65a66e788a 100644
--- a/packages/cli/src/config/keyBindings.ts
+++ b/packages/cli/src/config/keyBindings.ts
@@ -59,6 +59,7 @@ export enum Command {
   // App level bindings
   SHOW_ERROR_DETAILS = 'showErrorDetails',
   SHOW_FULL_TODOS = 'showFullTodos',
+  SHOW_FULL_OUTPUT = 'showFullOutput',
   TOGGLE_IDE_CONTEXT_DETAIL = 'toggleIDEContextDetail',
   TOGGLE_MARKDOWN = 'toggleMarkdown',
   TOGGLE_COPY_MODE = 'toggleCopyMode',
@@ -197,6 +198,7 @@ export const defaultKeyBindings: KeyBindingConfig = {
   // App level bindings
   [Command.SHOW_ERROR_DETAILS]: [{ key: 'f12' }],
   [Command.SHOW_FULL_TODOS]: [{ key: 't', ctrl: true }],
+  [Command.SHOW_FULL_OUTPUT]: [{ key: 'o', ctrl: true }],
   [Command.TOGGLE_IDE_CONTEXT_DETAIL]: [{ key: 'g', ctrl: true }],
   [Command.TOGGLE_MARKDOWN]: [{ key: 'm', command: true }],
   [Command.TOGGLE_COPY_MODE]: [{ key: 's', ctrl: true }],
@@ -299,6 +301,7 @@ export const commandCategories: readonly CommandCategory[] = [
     commands: [
       Command.SHOW_ERROR_DETAILS,
       Command.SHOW_FULL_TODOS,
+      Command.SHOW_FULL_OUTPUT,
       Command.TOGGLE_IDE_CONTEXT_DETAIL,
       Command.TOGGLE_MARKDOWN,
       Command.TOGGLE_COPY_MODE,
@@ -347,6 +350,8 @@ export const commandDescriptions: Readonly<Record<Command, string>> = {
   [Command.PASTE_CLIPBOARD]: 'Paste from the clipboard.',
   [Command.SHOW_ERROR_DETAILS]: 'Toggle detailed error information.',
   [Command.SHOW_FULL_TODOS]: 'Toggle the full TODO list.',
+  [Command.SHOW_FULL_OUTPUT]:
+    'Toggle display of full tool output when truncated.',
   [Command.TOGGLE_IDE_CONTEXT_DETAIL]: 'Toggle IDE context details.',
   [Command.TOGGLE_MARKDOWN]: 'Toggle Markdown rendering.',
   [Command.TOGGLE_COPY_MODE]:
diff --git a/packages/cli/src/test-utils/render.tsx b/packages/cli/src/test-utils/render.tsx
index 894fd065687..12c49efbaa4 100644
--- a/packages/cli/src/test-utils/render.tsx
+++ b/packages/cli/src/test-utils/render.tsx
@@ -133,6 +133,7 @@ const baseMockUiState = {
   mainAreaWidth: 100,
   terminalWidth: 120,
   currentModel: 'gemini-pro',
+  showFullOutput: false,
 };
 
 const mockUIActions: UIActions = {
diff --git a/packages/cli/src/ui/AppContainer.tsx b/packages/cli/src/ui/AppContainer.tsx
index 55ccc7438f5..c4ae3bb74d8 100644
--- a/packages/cli/src/ui/AppContainer.tsx
+++ b/packages/cli/src/ui/AppContainer.tsx
@@ -1009,6 +1009,7 @@ Logging in with Google... Restarting Gemini CLI to continue.
 
   const [showErrorDetails, setShowErrorDetails] = useState<boolean>(false);
   const [showFullTodos, setShowFullTodos] = useState<boolean>(false);
+  const [showFullOutput, setShowFullOutput] = useState<boolean>(false);
   const [renderMarkdown, setRenderMarkdown] = useState<boolean>(true);
 
   const [ctrlCPressCount, setCtrlCPressCount] = useState(0);
@@ -1230,6 +1231,13 @@ Logging in with Google... Restarting Gemini CLI to continue.
         setShowErrorDetails((prev) => !prev);
       } else if (keyMatchers[Command.SHOW_FULL_TODOS](key)) {
         setShowFullTodos((prev) => !prev);
+      } else if (keyMatchers[Command.SHOW_FULL_OUTPUT](key)) {
+        setShowFullOutput((prev) => {
+          const newValue = !prev;
+          // Force re-render of static content to show/hide full output
+          refreshStatic();
+          return newValue;
+        });
       } else if (keyMatchers[Command.TOGGLE_MARKDOWN](key)) {
         setRenderMarkdown((prev) => {
           const newValue = !prev;
@@ -1498,6 +1506,7 @@ Logging in with Google... Restarting Gemini CLI to continue.
       constrainHeight,
       showErrorDetails,
       showFullTodos,
+      showFullOutput,
       filteredConsoleMessages,
       ideContextState,
       renderMarkdown,
@@ -1586,6 +1595,7 @@ Logging in with Google... Restarting Gemini CLI to continue.
       constrainHeight,
       showErrorDetails,
       showFullTodos,
+      showFullOutput,
       filteredConsoleMessages,
       ideContextState,
       renderMarkdown,
diff --git a/packages/cli/src/ui/components/AnsiOutput.tsx b/packages/cli/src/ui/components/AnsiOutput.tsx
index d31ae62b28a..398ee828b97 100644
--- a/packages/cli/src/ui/components/AnsiOutput.tsx
+++ b/packages/cli/src/ui/components/AnsiOutput.tsx
@@ -8,8 +8,6 @@ import type React from 'react';
 import { Box, Text } from 'ink';
 import type { AnsiLine, AnsiOutput, AnsiToken } from '@google/gemini-cli-core';
 
-const DEFAULT_HEIGHT = 24;
-
 interface AnsiOutputProps {
   data: AnsiOutput;
   availableTerminalHeight?: number;
@@ -21,11 +19,11 @@ export const AnsiOutputText: React.FC<AnsiOutputProps> = ({
   availableTerminalHeight,
   width,
 }) => {
-  const lastLines = data.slice(
-    -(availableTerminalHeight && availableTerminalHeight > 0
-      ? availableTerminalHeight
-      : DEFAULT_HEIGHT),
-  );
+  // When availableTerminalHeight is undefined, show all lines
+  const lastLines =
+    availableTerminalHeight !== undefined && availableTerminalHeight > 0
+      ? data.slice(-availableTerminalHeight)
+      : data;
   return (
     <Box flexDirection="column" width={width} flexShrink={0}>
       {lastLines.map((line: AnsiLine, lineIndex: number) => (
diff --git a/packages/cli/src/ui/components/messages/ToolGroupMessage.tsx b/packages/cli/src/ui/components/messages/ToolGroupMessage.tsx
index d41ff534d02..8194f911ffb 100644
--- a/packages/cli/src/ui/components/messages/ToolGroupMessage.tsx
+++ b/packages/cli/src/ui/components/messages/ToolGroupMessage.tsx
@@ -5,8 +5,9 @@
  */
 
 import type React from 'react';
-import { useMemo } from 'react';
+import { useMemo, useState, useEffect } from 'react';
 import { Box, Text } from 'ink';
+import * as fs from 'node:fs/promises';
 import type { IndividualToolCallDisplay } from '../../types.js';
 import { ToolCallStatus } from '../../types.js';
 import { ToolMessage } from './ToolMessage.js';
@@ -16,6 +17,7 @@ import { theme } from '../../semantic-colors.js';
 import { SHELL_COMMAND_NAME, SHELL_NAME } from '../../constants.js';
 import { SHELL_TOOL_NAME } from '@google/gemini-cli-core';
 import { useConfig } from '../../contexts/ConfigContext.js';
+import { useUIState } from '../../contexts/UIStateContext.js';
 
 interface ToolGroupMessageProps {
   groupId: number;
@@ -37,6 +39,37 @@ export const ToolGroupMessage: React.FC<ToolGroupMessageProps> = ({
   activeShellPtyId,
   embeddedShellFocused,
 }) => {
+  const { showFullOutput } = useUIState();
+  const [fullOutputContents, setFullOutputContents] = useState<
+    Record<string, string>
+  >({});
+
+  // Load full output file contents when showFullOutput is toggled on
+  useEffect(() => {
+    if (!showFullOutput) {
+      setFullOutputContents({});
+      return;
+    }
+
+    const loadOutputFiles = async () => {
+      const contents: Record<string, string> = {};
+      for (const tool of toolCalls) {
+        if (tool.outputFile) {
+          try {
+            const content = await fs.readFile(tool.outputFile, 'utf-8');
+            contents[tool.callId] = content;
+          } catch {
+            contents[tool.callId] = `[Error reading file: ${tool.outputFile}]`;
+          }
+        }
+      }
+      setFullOutputContents(contents);
+    };
+
+    // eslint-disable-next-line @typescript-eslint/no-floating-promises
+    loadOutputFiles();
+  }, [showFullOutput, toolCalls]);
+
   const isEmbeddedShellFocused =
     embeddedShellFocused &&
     toolCalls.some(
@@ -167,10 +200,27 @@ export const ToolGroupMessage: React.FC<ToolGroupMessageProps> = ({
                   />
                 )}
               {tool.outputFile && (
-                <Box>
-                  <Text color={theme.text.primary}>
-                    Output too long and was saved to: {tool.outputFile}
+                <Box flexDirection="column">
+                  <Text color={theme.text.secondary}>
+                    Output saved to: {tool.outputFile}
+                    {!showFullOutput && ' (Press Ctrl+O to view full output)'}
                   </Text>
+                  {showFullOutput && fullOutputContents[tool.callId] && (
+                    <Box
+                      flexDirection="column"
+                      marginTop={1}
+                      borderStyle="single"
+                      borderColor={theme.border.default}
+                      paddingX={1}
+                    >
+                      <Text color={theme.text.accent} bold>
+                        ─── Full Output ───
+                      </Text>
+                      <Text color={theme.text.primary} wrap="wrap">
+                        {fullOutputContents[tool.callId]}
+                      </Text>
+                    </Box>
+                  )}
                 </Box>
               )}
             </Box>
diff --git a/packages/cli/src/ui/components/messages/ToolResultDisplay.tsx b/packages/cli/src/ui/components/messages/ToolResultDisplay.tsx
index 49002d50e92..36f6ddde52a 100644
--- a/packages/cli/src/ui/components/messages/ToolResultDisplay.tsx
+++ b/packages/cli/src/ui/components/messages/ToolResultDisplay.tsx
@@ -41,15 +41,17 @@ export const ToolResultDisplay: React.FC<ToolResultDisplayProps> = ({
   terminalWidth,
   renderOutputAsMarkdown = true,
 }) => {
-  const { renderMarkdown } = useUIState();
+  const { renderMarkdown, showFullOutput } = useUIState();
   const isAlternateBuffer = useAlternateBuffer();
 
-  const availableHeight = availableTerminalHeight
-    ? Math.max(
-        availableTerminalHeight - STATIC_HEIGHT - RESERVED_LINE_COUNT,
-        MIN_LINES_SHOWN + 1, // enforce minimum lines shown
-      )
-    : undefined;
+  // When showFullOutput is true, don't limit the height
+  const availableHeight =
+    showFullOutput || !availableTerminalHeight
+      ? undefined
+      : Math.max(
+          availableTerminalHeight - STATIC_HEIGHT - RESERVED_LINE_COUNT,
+          MIN_LINES_SHOWN + 1, // enforce minimum lines shown
+        );
 
   // Long tool call response in MarkdownDisplay doesn't respect availableTerminalHeight properly,
   // so if we aren't using alternate buffer mode, we're forcing it to not render as markdown when the response is too long, it will fallback
diff --git a/packages/cli/src/ui/components/shared/MaxSizedBox.tsx b/packages/cli/src/ui/components/shared/MaxSizedBox.tsx
index 86b36cd28d4..0ff9821479f 100644
--- a/packages/cli/src/ui/components/shared/MaxSizedBox.tsx
+++ b/packages/cli/src/ui/components/shared/MaxSizedBox.tsx
@@ -188,14 +188,14 @@ export const MaxSizedBox: React.FC<MaxSizedBoxProps> = ({
       {totalHiddenLines > 0 && overflowDirection === 'top' && (
         <Text color={theme.text.secondary} wrap="truncate">
           ... first {totalHiddenLines} line{totalHiddenLines === 1 ? '' : 's'}{' '}
-          hidden ...
+          hidden (Ctrl+O to show all) ...
         </Text>
       )}
       {visibleLines}
       {totalHiddenLines > 0 && overflowDirection === 'bottom' && (
         <Text color={theme.text.secondary} wrap="truncate">
           ... last {totalHiddenLines} line{totalHiddenLines === 1 ? '' : 's'}{' '}
-          hidden ...
+          hidden (Ctrl+O to show all) ...
         </Text>
       )}
     </Box>
diff --git a/packages/cli/src/ui/contexts/UIStateContext.tsx b/packages/cli/src/ui/contexts/UIStateContext.tsx
index 34e6262f306..173ced9451c 100644
--- a/packages/cli/src/ui/contexts/UIStateContext.tsx
+++ b/packages/cli/src/ui/contexts/UIStateContext.tsx
@@ -128,6 +128,7 @@ export interface UIState {
   embeddedShellFocused: boolean;
   showDebugProfiler: boolean;
   showFullTodos: boolean;
+  showFullOutput: boolean;
   copyModeEnabled: boolean;
   warningMessage: string | null;
   bannerData: {
diff --git a/packages/cli/src/ui/keyMatchers.test.ts b/packages/cli/src/ui/keyMatchers.test.ts
index 0982e84b2ac..047950f02b3 100644
--- a/packages/cli/src/ui/keyMatchers.test.ts
+++ b/packages/cli/src/ui/keyMatchers.test.ts
@@ -79,6 +79,7 @@ describe('keyMatchers', () => {
       key.ctrl && key.name === 'f',
     [Command.EXPAND_SUGGESTION]: (key: Key) => key.name === 'right',
     [Command.COLLAPSE_SUGGESTION]: (key: Key) => key.name === 'left',
+    [Command.SHOW_FULL_OUTPUT]: (key: Key) => key.ctrl && key.name === 'o',
   };
 
   // Test data for each command with positive and negative test cases
@@ -336,6 +337,11 @@ describe('keyMatchers', () => {
       positive: [createKey('f', { ctrl: true })],
       negative: [createKey('f')],
     },
+    {
+      command: Command.SHOW_FULL_OUTPUT,
+      positive: [createKey('o', { ctrl: true })],
+      negative: [createKey('o'), createKey('t', { ctrl: true })],
+    },
   ];
 
   describe('Data-driven key binding matches original logic', () => {