Louis Rosier started out driving a lorry for his father, and he competed in hillclimb events while in his twenties, and at the same time opened his own garage selling Renaults and Talbots. In 1938, by which time he was 32, he switched to cars with hillclimbs and an outing at the Le Mans 24-Hour.

In the war he worked with the French Resistance - his wife and daughter were taken hostage and sent to Germany, and after the war ended he travelled to Germany to find them.

Driving a Talbot, he soon made his mark in motor-racing following World War Two. His first win came at Albi in 1947. He won the Belgian GP in 1948 featured in both the 1948 and 1949 British Grands Prix, finishing fourth and third, and in 1949 also scored a good win in an International Grand Prix at Spa-Francorchamps. He won the French Championship every year between 1949 and 1952.

He featured in the early days of the FIA World Championship, winning the non-championship Dutch Grand Prix in 1950 and 1951 as well as the Le Mans 24-Hour in 1950. However, a win in a championship F1 race eluded him.

He was the owner and manager of the Ecurie Rosier team. Originally setup to run Rosier's Talbot-Lago T26 (for either Rosier or a guest driver), and later evolved to an actual team running 250Fs and finally Ferrari 500s simultaneously for Rosier and another driver. Throughout the 1950s, Écurie Rosier provided drives in Formula One for Henri Louveau, Georges Grignard, Louis Chiron, Maurice Trintignant, André Simon and Robert Manzon.

In 1956 he spun his Ferrari at Le Mans and suffered serious internal injuries when it overturned. He died three weeks later.