The SPAD S.XIII first flew on 4 April 1917, with deliveries to the French Air Service starting in the next month. The new fighter played an important part in the French plans for its fighter force, being expected to replace the SPAD S.VII, as well as the few remaining Nieuport fighters in front line service. Deliveries were much slower than expected, however, with 764 delivered by the end of March 1918 compared with a planned 2,230. The S.XIII eventually equipped virtually every French fighter squadron, 74 Escadrilles using the SPAD during the First World War. At the end of the war, plans were underway to replace the S.XIII with fighters using the 300 hp (220 kW) Hispano-Suiza 8F, such as the Nieuport-Delage NiD 29, the SPAD S.XX and the Sopwith Dolphin II, but the SPAD S.XIII remained in service with France as a fighter until 1923. Other Allied forces were quick to adopt the new fighter as well, with SPAD XIIIs equipping 15 of the 16 operational American pursuit squadrons at the Armistice. Nearly half of the 893 purchased for the United States Army Air Service were still in service in 1920. After the war, it was also exported to Japan, Poland and Czechoslovakia. In the United States, some SPAD XIIIs were re-engined with 180 hp Wright-Hispano engines to improve reliability and to prepare pilots for the new Thomas-Morse MB-3 fighter (which used SPAD-type wings in its construction) in 1922.
The S.XIII was flown by famous French fighter pilots such as Georges Guynemer and Rene Fonck, and also by Italian ace Francesco Baracca. Aces of the United States Army Air Service who flew the Spad XIII include Eddie Rickenbacker (America's leading World War I ace with 26 confirmed victories) and Frank Luke (18 victories).
In December 1917, No 23 Squadron of the Royal Flying Corps equipped with the SPAD S.XIII, retaining them until April 1918 when it re-equipped with the Sopwith Dolphin, while No. 19 Squadron (officially equipped with the earlier S.VII) also operated at least one SPAD S.XIII.