The SU-76M virtually replaced infantry tanks in the close support role. Its thin armour and open top made it vulnerable to antitank weapons, grenades, and small arms. Its light weight and low ground pressure gave it good mobility.
The SU-76M combined three main battlefield roles: light assault gun, mobile anti-tank weapon and mobile gun for indirect fire. As a light assault gun, the SU-76M was well-regarded by Soviet infantrymen (in contrast with their own crews). It had more powerful weapons than any previous light tank for close support and communication between infantry and the SU-76M crew was simple due to the open crew compartment. This was extremely useful in urban combat where good teamwork between infantry and AFVs was a key to success. Although the open compartment was highly vulnerable to small arms fire and hand grenades, it very often saved the crew's lives in the case of a hit by a Panzerfaust, whose concussion blast would mean death in an enclosed vehicle.
The SU-76M was effective against any medium or light German tank. It could also knock out the Panther tank with a flank shot, but the ZiS-3 gun was not effective against Tiger tanks. Soviet manuals for SU-76M crews usually instructed the gunner to aim for the tracks or gun barrels when facing Tigers. To improve the SU-76M's anti-armour capabilities, armour-piercing composite rigid (APCR) and hollow charge projectiles were introduced. This gave the SU-76M a better chance against heavily armoured German vehicles. A low profile, a low noise signature and good mobility were other advantages of the SU-76M. This was ideal for organizing ambushes and sudden flank or rear strikes in close combat, where the ZiS-3 gun was sufficient against most German armoured fighting vehicles.
The maximum elevation angle of the ZiS-3 was the highest of all Soviet self-propelled guns. The maximum indirect fire distance was nearly 17 km. SU-76Ms were sometimes used as light artillery vehicles (like the German Wespe) for bombardments and indirect fire support. However the power of the 76.2 mm shells was not sufficient in many cases.
The SU-76M was the single Soviet vehicle able to operate in swamps with minimal support from engineers. During the Belarus liberation campaign in 1944 it was extremely useful for organizing surprise attacks through swamps; bypassing heavy German defenses on firmer ground. Usually only lightly armed infantry could pass through large swampy areas. With SU-76M support, Soviet soldiers and engineers could effectively destroy enemy strongpoints and continue to advance.
The SU-76M had a large number of ammunition types. They included armour-piercing (usual, with ballistic nose and subcaliber hyper-velocity), hollow charge, high explosive, fragmentation, shrapnel and incendiary projectiles. This made the SU-76M an excellent multi-purpose light armoured fighting vehicle.
One famous crewman was Rem Nikolaevich Ulanov. In his younger days he was a mechanic-driver and later a commander of a SU-76. He and some other soldiers called their SU-76 Columbina after the female Renaissance Italian Commedia dell'Arte personage.
After World War II, the SU-76 was used by Communist forces in the Korean War. A small number of SU-76Ms were captured and used by the South after the landing of Incheon.