Franc Rozman was born in the Carniolan village of Spodnje Pirniče near Ljubljana, in what was then the Austro-Hungarian Monarchy (now in Slovenia) in a Slovene working-class family. His father Franc Rozman was a railway track-worker, while his mother Marjana (née Stare) was a housewife. He was the third of four children, with two elder sisters, Marjeta and Terezija, and a younger brother, Martin.
At the age of three, Rozman's father died on the Eastern Front, where he fought as a soldier in the Austro-Hungarian Army. Rozman had a poor and hard childhood. His sisters Marjeta and Terezija were sent to an orphanage, while Franc and his brother Martin remained in Pirniče. At the age of 15, he worked in a tavern and then trained as an apprentice baker. As a young boy he had great enthusiasm for a military career, but his application to the military school was rejected. In spring 1932, he did his military service in the Royal Yugoslav army.
In 1935, after the Italian invasion of Ethiopia, Rozman tried unsuccessfully to join the Ethiopian forces fighting the Italian invaders. Soon after the outbreak of the Spanish Civil War, he decided to travel to Spain. Rozman was among the first Yugoslav volunteers in Spain, where he, on 1 October 1936 joined the International Brigades. In November 1936 he became a member of the Spanish Communist Party. In Jarama he completed non commissioned officers' school, became a lieutenant and a commander of a company, then captain and commander of a battalion. His comrades in arms remembered him as an energetic and earnest person.
After the Spanish Civil War Rozman was imprisoned in France. He became a member of the Yugoslav Communist Party in 1939. In April 1941 he was imprisoned and sentenced to forced labor in Germany. In July the same year he fled Germany and returned to Yugoslavia.
For a while, Rozman lived with an activist of the Liberation Front of the Slovenian People. In early December 1941, he visited his youngest brother Martin, after which he joined the Slovene partisan resistance. Soon he became a military instructor with the High Command of the Slovene partisan forces. He was given the task of setting up the Styrian Battalion (Štajerski bataljon), which would consist of the partisan troops, the Revirje and the Savinja companies (Revirske in Savinjske čete), which were active in Styria in the autumn of 1941. He participated in the attack on Šoštanj and later in the Battle of Čreta. The Germans repeatedly tried to liquidate Rozman, setting many ambushes.
In the April 1942 Rozman became the commander of a Slovene partisan brigade, established on April 5, 1942 at Kremenik in Lower Carniola, and numbering more than 300 fighters. Measured by composition, organization, training, and fighting power, this was the most powerful Slovene partisan unit at that time.
On 13 July 1943, he became a commander of the High Command of the Slovene partisan army with the rank of lieutenant general (generallajtnant), which he held up to his death.
Rozman died in White Carniola as a consequence of a serious wound received while testing new mortar weapons sent to the partisans by their British Allies. There were some rumors that he was killed by sabotage by the Chetnik military authorities or at the behest of Partisan commander Arso Jovanović, but they have never been proven. He was proclaimed a People's Hero of Yugoslavia on 11 November 1944.