21 Electronic Warfare Regiment (French: 21e Régiment de guerre électronique) is a Royal Canadian Corps of Signals regiment in the Canadian Army, based at CFB Kingston, Ontario.

[1] 21 EW Regt exists to provide trained army electronic warfare operators and support personnel to the Canadian Armed Forces.

214 Electronic Warfare Squadron is the only Reserve electronic warfare squadron within the Canadian Armed Forces that is a part of a Regular Force regiment.

[2] The regiment participated in the Battle of Mosul where it intercepted, deciphered and jammed ISIL communications.

[5] The regiment later was deployed in Latvia where it instructed NATO allies and other Canadian units in electronic warfare.