Italy declared war on Austria-Hungary on 23 May 1915. The Antonio Mosto was commissioned seven weeks later. Her early service was in the Adriatic, where the Italian and Austro-Hungarian navies contested control of the sea routes between Italy's Adriatic ports and the Albanian coast. On 13 August 1915, sailing with a sister ship and a French destroyer, she took part in the search for an Austro-Hungarian submarine that had attacked an Italian auxiliary cruiser east of Brindisi; the French destroyer Bisson found the submarine disabled on the surface and sank her. In December 1915, the Antonio Mosto was among Allied warships that put to sea to intercept an Austro-Hungarian force that had bombarded the harbour at Durrës. The subsequent clash — known as the First Battle of Durazzo — saw French destroyers sink an Austro-Hungarian ship. The Antonio Mosto did not play a decisive role but was there, accumulating the kind of experience that convoy warships accumulate: long hours at sea, near misses, and the particular vigilance demanded by waters where submarines operated.

The largest naval action of the Adriatic campaign of the First World War came on 15 May 1917, when Austro-Hungarian forces staged a two-pronged attack against the Otranto Barrage — the anti-submarine barrier the Allies had stretched across the strait — and against Italian convoy traffic from Greece to Albania. The Antonio Mosto got underway from Otranto at 04:50, heading northeast with an Italian destroyer and the British light cruiser HMS Bristol to intervene. When the Italian scout cruiser Aquila was immobilised by a hit around 09:05, the Antonio Mosto and HMS Bristol placed themselves between the damaged Aquila and the Austro-Hungarian ships, opening fire at a range of 8,500 metres. The Austro-Hungarians withdrew to the northwest, pursued by the Allied ships until the chase had to be broken off at 12:05 when the formation neared Cattaro, from which Austro-Hungarian reinforcements had sortied. The battle was inconclusive but intense. All the major warships involved took some damage. The Antonio Mosto came through and returned to port.

After 1918, the Antonio Mosto's armament was revised and her displacement rose to 900 tonnes. In 1929 she was reclassified as a torpedo boat, the same designation given to her sometime companion the Angelo Bassini. When Italy entered the Second World War in June 1940, the Antonio Mosto was still in service, now assigned to convoy escort duties in the Mediterranean and Adriatic. She participated in the campaign supporting Italian forces in the Greco-Italian War, ferrying supplies and personnel along the Albanian and Greek coast routes. In April 1941 she escorted a convoy from Palermo to Tripoli. On 9 July 1941, moored at Tripoli during a British air raid, a British aircraft shot down by anti-aircraft fire crashed onto her deck, causing serious damage. She was repaired and returned to service. On 6 November 1942, she left Taranto with the Angelo Bassini to escort the tanker Giorgio toward Patras on the Greek coast. The two ships, which had served in the same waters for years, parted there.

On 8 September 1943, Italy announced an armistice with the Allies and switched sides in the war. Nazi Germany immediately began Operation Achse — the forcible disarmament of Italian military units and the occupation of Italian-held territory. Ships that hesitated or were caught in German-controlled ports were seized. The Antonio Mosto moved quickly to Palermo, by then in Allied hands, and then on 20 September 1943 sailed to Malta with many other Italian vessels. She returned to Italy on 5 October. For the remainder of the war, she served as a unit of the Italian Co-belligerent Navy — Italy fighting now alongside the Allies rather than against them — on escort duty in the waters off Tunisia. She was one of the very few ships of her vintage and class to have survived both the years of fighting as an Axis vessel and the dangerous days immediately following the armistice.

The Italian monarchy was abolished in 1946. The Regia Marina became the Marina Militare of the Italian Republic. The Antonio Mosto stayed in service under both flags. In 1953, she was reclassified as a minesweeper and given the pennant number M 5335 — a role suited to a ship now ageing but still capable of careful, deliberate work. She was the last of the Rosolino Pilo-class ships to remain in service. When she was finally stricken on 15 December 1958 and subsequently scrapped, she had been in naval service for forty-three years, across two world wars, three forms of government, and enough operations in the Adriatic and Ionian to fill a record that most destroyers never came close to equalling. What that record looked like for the men who served aboard her — the engineers, the sailors, the officers who rotated in and out across four decades — is not recorded in the surviving documents. The ship's history is what remains.