Luther Johnson (born April 11, 1939, Itta Bena, Mississippi, United States) is an American 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.