The Treaty of Athis-sur-Orge was a peace treaty signed on June 23, 1305 between King Philip IV of France and Robert III of Flanders. The treaty was signed at Athis-sur-Orge after the Battle of Mons-en-Pévèle and concluded the Franco-Flemish War (1297-1305).
Based on the terms of the treaty, the cities of Lille, Douai, and Béthune were allocated to the French crown. In return, Flanders was allowed to preserve its independence as a fief of the kingdom.