The Formation was raised as 21 Indian Infantry Division at Secunderabad on 03 Apr 1943 and subsequently employed under Gen William Slim's 14th Army during 'Reconquest of Burma'.

The Formation was demobilised on 10 Aug 1944 and re-raised as 21 Infantry Division on 01 Jul 1976, at Rangia.

The Formation moved to Tenga as part of forward posture in Kameng Sector and remained there till 1990.

Successful conduct of CI/ CT operations resulted in ULFA announcing a unilateral ceasefire in Jan 1992 and signing of Bodo Agreements in 1993, 2003 and 2020.

During the course, the Division HQ moved to Umroi in Dec 2016 and was again re-located to Rangia in Mar 2018.