How to Get a Mob Spawner in Minecraft

Guide Java Bedrock

Quick answer: You cannot get a monster spawner in Survival, even with Silk Touch. A spawner cannot be moved from where it generated. Mine it with a pickaxe for 15-43 XP, or find one in a monster room, mineshaft or woodland mansion and build your farm around it. In Creative, use /give or the creative inventory.

What you need

Pickaxe (to break it for XP)
Torches (to disable it)
Creative mode or cheats (to obtain one)

Step by step

Know the limit: monster spawners are not obtainable in Survival, and Silk Touch does not help. They cannot be moved.
Find one: monster rooms hold one spawner (zombie 50%, skeleton 25%, spider 25%), mineshafts have cave spider spawners among cobwebs, woodland mansions may have a spider spawner in a rare secret room, strongholds have a silverfish spawner in the end portal room, nether fortresses have one or two blaze spawners, and bastion remnants have a magma cube spawner.
A spawner activates when you are within 16 blocks. It tries to spawn 4 mobs around it, then waits 10 to 39.95 seconds before trying again.
Mine it with any pickaxe to get 15-43 XP. Anything else drops nothing.
To build a farm, leave the spawner in place and surround its spawning volume (up to 9 x 3 x 9 blocks) with your trap or kill chamber.
To switch it off, use light: for mobs that only spawn in the dark (light level 0), a torch on any side or the top of the spawner stops it across the whole spawn area. Blaze and silverfish spawners need light level 12, and magma cube spawners need the spawn area filled with solid blocks.
In Creative, take a spawner from the creative inventory or use /give. It starts empty, and you set the mob with a spawn egg on the placed block.

Java vs Bedrock

Spawner rules differ slightly by edition. In Bedrock Edition some animals need light level 7 or more in spawners, and turtles ignore biome and light conditions there. In Java Edition turtle spawners only spawn turtles on sand less than 4 blocks above sea level.

Versions: A spawner always drops 15-43 XP when mined with a pickaxe in current versions.

Frequently asked questions

Can you get a mob spawner with Silk Touch?

No. Monster spawners cannot be obtained in Survival, even with Silk Touch.

Where do you find mob spawners?

In monster rooms, mineshafts (cave spiders), woodland mansions (a spider, rarely), strongholds (silverfish), nether fortresses (blazes) and bastion remnants (a magma cube).

How do you stop a mob spawner?

Place a torch on any side or the top for mobs that spawn only in the dark. Other mobs need other methods, such as blocking the spawn area.

How many mobs does a spawner make?

It tries to spawn 4 mobs, then waits 10 to 39.95 seconds. It often makes fewer because spawn conditions must be met.

How far away must I be for it to work?

Within 16 blocks of the spawner.