He was the highest scoring driver in the inaugural World Rally Championship in 1973 and the only one to win three events.

He most frequently competed in an Alpine Renault A110; the French often refer to him and his fellow drivers Jean-Pierre Nicolas, Bernard Darniche, and Jean-Claude Andruet as Les Mousquetiers ("The Musketeers").

[1] Thérier's first international victory came at the wheel of an Alpine A110, at the Rallye Sanremo and the Acropolis Rally in 1970.

He also won the 1974 Press-on-Regardless Rally in the United States driving a Renault 17 Gordini, and the 1980 Tour de Corse behind the wheel of a Porsche 911 SC.

His career lasted until early 1985 when he suffered severe injuries while participating in the 1985 Paris to Dakar rally.