How to Change Difficulty in Minecraft

Guide Java Bedrock

Quick answer: Run /difficulty peaceful (or easy, normal, hard) with cheats on - no cheats needed in Java singleplayer settings. Bedrock: world settings > Difficulty dropdown. Hardcore worlds are locked to Hard forever.

What you need

Java: world settings or cheats
Bedrock: world settings access (owner/operator on servers)
Nothing else

Step by step

Java without cheats: pause > Options > difficulty setting (or set it on the world-creation screen). Singleplayer lets you change it freely.
With cheats on either edition: /difficulty peaceful, /difficulty easy, /difficulty normal or /difficulty hard.
Peaceful removes hostile mobs and regenerates health; easy/normal/hard scale damage, hunger effects and zombie behaviors.
Bedrock: world settings > Difficulty dropdown - no cheats needed and achievements stay on.
Servers: the difficulty lives in server.properties (difficulty=normal) or set it live as an operator with /difficulty.
Hardcore warning: Hardcore worlds (Java creation option) are locked to Hard with one life - /difficulty cannot touch them.

Java vs Bedrock

Java changes difficulty without cheats in singleplayer. On Bedrock the settings dropdown does it without touching achievements. Locking difficulty (Java padlock button) forces cheats to unlock.

Versions: The four difficulties and the /difficulty command are identical across all current versions. Hardcore mode came to Bedrock in 1.21.

Frequently asked questions

Does changing difficulty disable achievements?

No - difficulty is a normal setting on both editions, not a cheat.

What does Peaceful remove?

Most hostile mobs despawn and stop spawning, and your health regenerates. Some mobs survive: the Ender Dragon fight changes, and shulkers stay.