Gallinaro is located in the Comino Valley and is crossed by Rio Mollo, a tributary river of Melfa. It borders the municipalities of Alvito, Atina, Picinisco, San Donato Val di Comino and Settefrati. The town is 21 kilometres (13 mi) from Sora, 25 kilometres (16 mi) from Cassino, 48 kilometres (30 mi) from Frosinone and 138 kilometres (86 mi) from Rome.