The Ausf G was the last production series of the StuG. Rolling off the assembly-line in December 1942, the Ausf G was produced until the end of the war, with no major design changes. In 1942, the decision was made to use Pz Kpfw III Fgst for StuG production, since the Pz Kpfw III was being phased out and replaced by the Panther. In response to this request, 165 Pz Kpfw III Ausf M Fgst were used as chassis for StuG Ausf G, with production from February to November 1943. In 1944, 173 Pz Kpfw III, returned to the factory for overhaul, were converted to StuG Ausf G.
The hull of the Ausf G remained unaltered from the design used for the Ausf F/8. The main design changes were to the superstructure. The roof was altered, and a cupola with periscopes was added for the commander, and a shield for the machine-gun was installed in front of the loader's hatch. The superstructure sides were now slanted, and slanted plates were added to protect the front of both panniers. Various improvements were instituted during the production run, including introduction of the Saukopf (sow's head) gun mantlet late in 1943, the coaxial machine-gun early in 1944, and the Nahverteidigungswaffe (close-in defence weapon) and remote-control machine-gun to the superstructure roof late in spring 1944. Vehicles issued to Funklenk Kompanien (Remote-Control Companies) were fitted with an additional radio aerial on the left front of the fighting compartment roof.
Twenty-eight independent Sturmgeschütz detachments, four divisional Sturmgeschütz detachments, two 2nd Funklenk companies and twelve Sturmgeschütz platoons (with Luftwaffe Field Divisions) were at the front in Russia at the start of the Kursk offensive. From the start of the war, the use of the assault-gun spread from Sturmgeschütz detachments to the other types of formations, including Panzer detachments, Panzerjäger detachments and Funklenk companies and detachments.