Lonesome Sundown was born on 12/12/1928 in the Dugas Plantation near Donaldsonville, Louisiana. His full birth name was Cornelius Green III. When he was 18, he moved to New Orleans. There he had several jobs including as a porter at a casino called the New Southport Club.
In 1948, he returned to Donaldsonville. After being inspired by Muddy Waters and John Lee Hooker, he took up guitar lessons from one of his cousins.
In 1953, after briefly working as a truck driver in Jeanerette, Louisiana he moved to work at the Gulf Oil Refinery in Port Arthur, Texas. He had begun to jam at local clubs.
In 1955, he was invited to sit in with Clifton Chenier and his band the Zydeco Ramblers at the Blue Moon Club in Lake Charles. Chenier asked him to join as a second guitarist. He toured with as far as Chicago and Los Angeles. Chenier's song "The Cat's Dreaming" was inspired by Green falling asleep during a session and where Green unsuccessfully auditioned for producer Bumps Blackwell. Later in 1955, Green got married and left the Zydeco Ramblers. He moved to Opelousas, Louisiana. There he began playing with Lloyd Reynauld and started to write his own material. He recorded a demo tape and took it to producer J. D. "Jay" Miller in Crowley. Miller was impressed and gave Green the stage name Lonesome Sundown.
In 1956 Sundown's debut single "Leave My Money Alone" was released by Excello Records after being produced by Miller. The follow single "Lonesome Whistler" was more successful than the first and Sundown would record with Miller for 8 years. Sundown would not have a chart hit, but his records sold in respectable figures. Sundown's style was nearer that of Muddy Waters than other Louisiana blues artists who were nearer the style of Jimmy Reed. His style was considered to be "Swamp Blues".
In 1965, Sundown retired from the music industry and worked as a laborer. He also joined Lord Jesus Christ of the Apostolic Faith Fellowship where he eventually became a minister.
In 1977, he came back into the recording studio to record the album "Been Gone Too Long" for Joliet Records. Unfortunately, the sales were disappointing. His last single was also that year and was the song "I Betcha".
In 1979, Sundown made an appearance at the New Orleans Jazz & Heritage Festival and he also toured Sweden and Japan with Philip Walker. After the tour, he retired again from the music industry.
In 1994 he suffered a stroke and was no longer able to speak.
In April 1995, Sundown died in Gonzales, Louisiana.
In 2000, he was posthumously inducted into the Louisiana Blues Hall of Fame.