During the 1990s, India decided to undergo an upgrade program for their fleet of MiG-21bis aircraft, based on the newly unveiled MiG-21-93 modernization package. After a lot of negotiation and prototyping, it was decided that with Mikoyan OKB's help, HAL (Hindustan Aeronautics) would produce the "kits" to upgrade the aircraft. The MiG-21Bis-UPG aircraft, affectionately named the "MiG-21 Bison" was a specially tailored upgrade package that left out some of the original upgrades of the 21-93, but also incorporated some indigenous avionics and systems that the original did not. One such system was the TARANG radar warning receiver and jammer suite. The Bisons were slated to remain in indian service as rear-line interceptors until at least 2025, however, due to political reasons, this was cut short and all MiG-21s in the IAF's fleet were retired in 2024.

The MiG-21 Bison (Great Britain) was introduced in Update "Seek & Destroy". As a premium aircraft, it provides a great alternative to the F-4J UK for researching the higher ranks of the tech tree. The MiG-21 Bison is a heavily upgraded MiG-21bis airframe, and at its battle rating, the extremities of such upgrade begin to show. While the aircraft has incredible weaponry and avionics for its battle rating, the missile count and overall flight performance begins to show its limits when facing superior aircraft in uptiers such as F-15s, Su-27s, and JAS-39s. The Bison is also one of the very few aircraft in-game fitted with a GTM (Air to Ground) tracking mode in its radar, allowing it to lock on to ground vehicles and maritime targets, and track their movement from far away. This, coupled with targeting of the KAB-500Kr TV guided bombs, allows the Bison to execute quick and precise interdiction strikes. Just be careful of the low amount of ordnance and countermeasures on this aircraft.