Directly developed from the earlier M11/39, the M13/40 was Italy's main tank used in World War II. The main difference between the two vehicles was the armament configuration, as designed realized that the heavier gun was better mounted in the turret rather than in the side of the hull where it would have only limited traverse. The turret was therefore enlarged to accommodate a two-man crew as well as a more powerful 47-mm gun (compared to the 37-mm gun of the M11/39). This gave it significantly improved tank-killing power, adequate enough to take on most British cruiser tanks, but still falling short when facing the more heavily armored infantry tanks like the Matilda and Valentine. Additionally, armor protection was increased for the hull front, but remained constrained by the riveted construction which was less effective than welded designs. An additional problem was the unreliable engine, the same SPA diesel used in the M11/39 but which was prone to breakdowns in desert conditions; this required the installment of a tropical filters in later variants. M13/40s saw extensive action in the Balkans and North Africa where they formed the core of Italy's armored units. Many were captured after battlefield defeats, and at one time were used to fully equip the British 6th RTR and the Australian 6th Cavalry. Attrition was heavy among M13/40 units but a small number survived the war and remained in service well into the post-war era.

The M13/40 was directly developed from the earlier M11/39, retaining the chassis but adding extra armor protection to the hull, as well as a new armament configuration. The unreliability of engine in the desert prompted an upgrade of the powerplant (which also featured tropical filters) in the M14/41. This was then followed by the M15/42 with a slightly longer hull and yet another engine upgrade. Armor protection was also increased slightly, and the longer barreled gun was more effective as well. A series of tank destroyer designs using the M13/40 hull were also built, but are described separately as the Semovente M41.