Filipović was born on 27 January 1916 in Opuzen (in modern-day Dubrovnik-Neretva County, Croatia), in the last days of the Austro-Hungarian Empire. Before the outbreak of the Second World War he lived in Mostar, Bosnia and Herzegovina, and Kragujevac, Serbia, then both part of the Kingdom of Yugoslavia. He joined the workers' movement in 1937, but he was arrested in 1939 and sentenced to a year in prison. He later joined the Communist Party of Yugoslavia in 1940.