Luther Johnson (April 11, 1939, Itta Bena, Mississippi) is a Chicago Blues singer and guitarist, who performs under the name Luther "Guitar Junior" Johnson.

Johnson moved to Chicago with his family in 1955. During the 1960s, he performed with Magic Sam. He also performed in Muddy Waters's band from 1972 to 1980. In 1980, four of his songs were included on an anthology by Alligator Records.

Johnson moved to the East Coast and began fronting his own band, the Magic Rockers. His "Walkin' The Dog," was recorded live at the Montreux Festival's Blues Night. Johnson won a Grammy Award in 1985 for Best Traditional Blues Album for his part in Blues Explosion.

Johnson appeared on three albums by The Nighthawks. He now lives in New Hampshire.

Earlier in his career, Lonnie Brooks also performed under the name Guitar Junior.