Her first mission was the supply of Italian troops stationed in Libya, sailing between Brindisi and Benghazi.

On 12 June 1942, on passage to Benghazi, the ship was substantially damaged by Allied aircraft and towed to Taranto for repairs.

On 9 September 1943, the day after the Armistice between Italy and Allied armed forces, Mario Roselli was confiscated by the Germans and used to transport Italian POWs to Venice and Trieste.

At 7:15 on 10 October, when the boarding was almost finished, an Allied aircraft appeared and immediately attacked the ship and motorboats.

Another fell directly through an open hatch into the hold of the ship crowded with Italians, and exploded, causing terrible carnage.