diff --git a/src/rollup/types.d.ts b/src/rollup/types.d.ts
index aeeb213daf7..3dcd8ab0223 100644
--- a/src/rollup/types.d.ts
+++ b/src/rollup/types.d.ts
@@ -15,8 +15,6 @@ export interface RollupError extends RollupLog {
 	watchFiles?: string[];
 }
 
-export type RollupWarning = RollupLog;
-
 export interface RollupLog {
 	binding?: string;
 	cause?: unknown;
@@ -598,7 +596,6 @@ export interface NormalizedInputOptions {
 	maxParallelFileOps: number;
 	moduleContext: (id: string) => string;
 	onLog: LogHandler;
-	onwarn: (warning: RollupLog) => void;
 	perf: boolean;
 	plugins: Plugin[];
 	preserveEntrySignatures: PreserveEntrySignaturesOption;
diff --git a/src/utils/options/mergeOptions.ts b/src/utils/options/mergeOptions.ts
index a77e3ad937a..9e5448880ac 100644
--- a/src/utils/options/mergeOptions.ts
+++ b/src/utils/options/mergeOptions.ts
@@ -53,7 +53,7 @@ export async function mergeOptions(
 	const logLevel = config.logLevel || LOGLEVEL_INFO;
 	const onLog = getOnLog(config, logLevel, printLog);
 	const log = getLogger(plugins, onLog, watchMode, logLevel);
-	const inputOptions = await mergeInputOptions(config, command, plugins, log, onLog);
+	const inputOptions = mergeInputOptions(config, command, plugins, log, onLog);
 	if (command.output) {
 		Object.assign(command, command.output);
 	}
@@ -75,14 +75,14 @@ export async function mergeOptions(
 			...Object.keys(commandAliases),
 			'bundleConfigAsCjs',
 			'config',
+			'configPlugin',
 			'environment',
+			'failAfterWarnings',
 			'filterLogs',
 			'plugin',
 			'silent',
-			'failAfterWarnings',
 			'stdin',
-			'waitForBundleInput',
-			'configPlugin'
+			'waitForBundleInput'
 		],
 		'CLI flags',
 		log,
diff --git a/src/utils/options/normalizeInputOptions.ts b/src/utils/options/normalizeInputOptions.ts
index 18b9b59fa25..9ba2c640b79 100644
--- a/src/utils/options/normalizeInputOptions.ts
+++ b/src/utils/options/normalizeInputOptions.ts
@@ -8,7 +8,7 @@ import type {
 import { EMPTY_ARRAY } from '../blank';
 import { ensureArray } from '../ensureArray';
 import { getLogger } from '../logger';
-import { LOGLEVEL_INFO, LOGLEVEL_WARN } from '../logging';
+import { LOGLEVEL_INFO } from '../logging';
 import { error, logInvalidOption } from '../logs';
 import { resolve } from '../path';
 import { URL_TREESHAKE, URL_TREESHAKE_MODULESIDEEFFECTS } from '../urls';
@@ -55,7 +55,6 @@ export async function normalizeInputOptions(
 		maxParallelFileOps,
 		moduleContext: getModuleContext(config, context),
 		onLog,
-		onwarn: warning => onLog(LOGLEVEL_WARN, warning),
 		perf: config.perf || false,
 		plugins,
 		preserveEntrySignatures: config.preserveEntrySignatures ?? 'exports-only',
@@ -67,7 +66,7 @@ export async function normalizeInputOptions(
 
 	warnUnknownOptions(
 		config,
-		[...Object.keys(options), 'watch'],
+		[...Object.keys(options), 'onwarn', 'watch'],
 		'input options',
 		onLog,
 		/^(output)$/
diff --git a/test/function/samples/logging/log-from-plugin-options-onlog-onwarn/_config.js b/test/function/samples/logging/log-from-plugin-options-onlog-onwarn/_config.js
index d52c011648f..7e1762a9a42 100644
--- a/test/function/samples/logging/log-from-plugin-options-onlog-onwarn/_config.js
+++ b/test/function/samples/logging/log-from-plugin-options-onlog-onwarn/_config.js
@@ -36,18 +36,7 @@ module.exports = defineTest({
 			['onLog', 'info', { message: 'infoLog' }],
 			['info', 'infoLog'],
 			['onLog', 'debug', { message: 'debugLog' }],
-			['debug', 'debugLog'],
-			['onLog', 'warn', { message: 'warnWarn' }],
-			['onwarn', { message: 'warnWarn' }],
-			['warn', 'warnWarn'],
-			['onLog', 'warn', { message: 'warnWarn=' }],
-			['onwarn', { message: 'warnWarn=' }],
-			['onLog', 'warn', { message: 'warnWarn+=' }],
-			['onwarn', { message: 'warnWarn+=' }],
-			['warn', 'log was replaced'],
-			['onLog', 'warn', { message: 'warnWarn-' }],
-			['onLog', 'warn', { message: 'warnWarn+-' }],
-			['info', 'log was replaced']
+			['debug', 'debugLog']
 		]);
 		assert.strictEqual(logs[0][2].toString(), 'warnLog');
 		assert.strictEqual(logs[1][1].toString(), 'warnLog');
@@ -88,11 +77,6 @@ module.exports = defineTest({
 					options.onLog('warn', { message: 'warnLog+-' });
 					options.onLog('info', { message: 'infoLog' });
 					options.onLog('debug', { message: 'debugLog' });
-					options.onwarn({ message: 'warnWarn' });
-					options.onwarn({ message: 'warnWarn=' });
-					options.onwarn({ message: 'warnWarn+=' });
-					options.onwarn({ message: 'warnWarn-' });
-					options.onwarn({ message: 'warnWarn+-' });
 				}
 			}
 		]
diff --git a/test/function/samples/logging/log-from-plugin-options-onlog/_config.js b/test/function/samples/logging/log-from-plugin-options-onlog/_config.js
index 5afdcc30220..c133d591664 100644
--- a/test/function/samples/logging/log-from-plugin-options-onlog/_config.js
+++ b/test/function/samples/logging/log-from-plugin-options-onlog/_config.js
@@ -28,14 +28,7 @@ module.exports = defineTest({
 			['onLog', 'info', { message: 'infoLog' }],
 			['info', 'infoLog'],
 			['onLog', 'debug', { message: 'debugLog' }],
-			['debug', 'debugLog'],
-			['onLog', 'warn', { message: 'warnWarn' }],
-			['warn', 'warnWarn'],
-			['onLog', 'warn', { message: 'warnWarn-' }],
-			['onLog', 'warn', { message: 'warnWarn+-' }],
-			['debug', 'log was replaced'],
-			['onLog', 'warn', { message: 'warnWarn*-' }],
-			['info', 'log was replaced with string']
+			['debug', 'debugLog']
 		]);
 		assert.strictEqual(logs[0][2].toString(), 'warnLog');
 		assert.strictEqual(logs[2][2].toString(), '(fooPlugin plugin) fooFile (1:2) warnLog');
@@ -68,10 +61,6 @@ module.exports = defineTest({
 					options.onLog('warn', { message: 'warnLog*-' });
 					options.onLog('info', { message: 'infoLog' });
 					options.onLog('debug', { message: 'debugLog' });
-					options.onwarn({ message: 'warnWarn' });
-					options.onwarn({ message: 'warnWarn-' });
-					options.onwarn({ message: 'warnWarn+-' });
-					options.onwarn({ message: 'warnWarn*-' });
 				}
 			}
 		]
diff --git a/test/function/samples/logging/log-from-plugin-options-onwarn/_config.js b/test/function/samples/logging/log-from-plugin-options-onwarn/_config.js
index d06b2fc8995..7e7c98bf7c2 100644
--- a/test/function/samples/logging/log-from-plugin-options-onwarn/_config.js
+++ b/test/function/samples/logging/log-from-plugin-options-onwarn/_config.js
@@ -25,14 +25,7 @@ module.exports = defineTest({
 			['onwarn', { message: 'warnLog*-' }],
 			['warn', 'log was replaced with string'],
 			['info', 'infoLog'],
-			['debug', 'debugLog'],
-			['onwarn', { message: 'warnWarn' }],
-			['warn', 'warnWarn'],
-			['onwarn', { message: 'warnWarn-' }],
-			['onwarn', { message: 'warnWarn+-' }],
-			['warn', 'log was replaced'],
-			['onwarn', { message: 'warnWarn*-' }],
-			['warn', 'log was replaced with string']
+			['debug', 'debugLog']
 		]);
 		assert.strictEqual(logs[0][1].toString(), 'warnLog');
 		assert.strictEqual(logs[2][1].toString(), '(fooPlugin plugin) fooFile (1:2) warnLog');
@@ -65,10 +58,6 @@ module.exports = defineTest({
 					options.onLog('warn', { message: 'warnLog*-' });
 					options.onLog('info', { message: 'infoLog' });
 					options.onLog('debug', { message: 'debugLog' });
-					options.onwarn({ message: 'warnWarn' });
-					options.onwarn({ message: 'warnWarn-' });
-					options.onwarn({ message: 'warnWarn+-' });
-					options.onwarn({ message: 'warnWarn*-' });
 				}
 			}
 		]
diff --git a/test/function/samples/logging/log-from-plugin-options-simple/_config.js b/test/function/samples/logging/log-from-plugin-options-simple/_config.js
index 434e571dce2..607548a57aa 100644
--- a/test/function/samples/logging/log-from-plugin-options-simple/_config.js
+++ b/test/function/samples/logging/log-from-plugin-options-simple/_config.js
@@ -15,14 +15,12 @@ module.exports = defineTest({
 		assert.deepStrictEqual(logs, [
 			['warn', 'warnLog'],
 			['info', 'infoLog'],
-			['debug', 'debugLog'],
-			['warn', 'warnWarn']
+			['debug', 'debugLog']
 		]);
 		assert.deepStrictEqual(pluginLogs, [
 			['warn', { message: 'warnLog' }],
 			['info', { message: 'infoLog' }],
-			['debug', { message: 'debugLog' }],
-			['warn', { message: 'warnWarn' }]
+			['debug', { message: 'debugLog' }]
 		]);
 	},
 	options: {
@@ -36,7 +34,6 @@ module.exports = defineTest({
 					options.onLog('warn', { message: 'warnLog' });
 					options.onLog('info', { message: 'infoLog' });
 					options.onLog('debug', { message: 'debugLog' });
-					options.onwarn({ message: 'warnWarn' });
 				},
 				onLog(level, log) {
 					pluginLogs.push([level, log]);