Joseph Rosier (January 24, 1870 – October 7, 1951) was a United States senator from West Virginia.

Born in Wilsonburg, West Virginia, he attended the public schools and graduated from Salem College in 1895.

He was a teacher in the State normal school at Glenville, West Virginia from 1896 to 1897 and was a member of the faculty of the State Teachers' College at Fairmont, West Virginia from 1897 to 1900.

Rosier served from January 13, 1941, to November 17, 1942, when a duly elected successor qualified.

Rosier was an unsuccessful candidate for election to the unexpired term, and resumed his former pursuits.