The BT-7 was a significant improvement over the earlier BT tank designs that preceded it which were based on on the designs of J. W. Christie in the US. The BT-7 maintained its predecessors 45mm M1935 gun but with increased stowage as well as redesigned welded armor that was more prominently sloped. The turret design was also improved; although early vehicles retained the BT-5's cylindrical turret, a new conical turret originally designed for the T-26 was eventually incorporated. Like previous BT models, the BT-7 had the ability of having the tracks removed in order to run on the road wheels alone. However, this was not frequently performed by Red Army crews, especially during wartime. Mobility and speed were adequate, and later variants had the original gasoline engines replaced by diesels and some were fitted with schnorkels which enabled them to undertake deep fording operations. The BT-7 was first used in combat during the border conflict with Japan at Khalkin-Gol in 1939 and later in the 1939-40 Winter War against Finland. At the time of the German invasion in June 1941, the BT-7 was the most widespread tank in the Red Army inventory and therefore saw extensive action early in the conflict. Consequently, it would suffer severe losses given that it was inferior to the German PzKpfw III and IV. It was eventually phased out of front-line service once large numbers of T-34s could be fielded but it remained on hand until the end of the war where they had been converted to special purpose vehicles.

The BT-7 arose from combat experience during various border conflicts with Japan in 1934-35 where riveted armor of the earlier BT tanks proved to be vulnerable. The addition of twin horn periscopes led to the BT-7-2, while a more powerful V-2 diesel engine resulted in the BT-7M (initially designated BT-8). Other variants included the BT-7A close support vehicle with a 76.2-mm howitzer, the OP-7 flamethrower, and the BT-7TU commander's model. Numerous experimental variants were also conceived.