John Cooksey first attended the LaSalle High School and then studied until 1962 at Louisiana State University in Baton Rouge. At the same university he studied medicine until 1966. 28 years later he completed his studies at the University of Texas at Austin, where he studied business administration. Between 1967 and 1969 he was a soldier in the U.S. Air Force. He was stationed most of the time in Texas. In the meantime he was but offset to Thailand. Until 1972 he was a member of the Air Force Reserve. In the following years he worked as an ophthalmologist.
Politically Cooksey was a member of the Republican Party. In the congressional elections of 1996 he was in the fifth electoral district of Louisiana in the U.S. House of Representatives in Washington DC chosen, where he became the successor of Jim McCrery on 3 January 1997. After two re- election he was able to complete in Congress until January 3, 2003, three legislative periods. In 2002 Cooksey opted not to run again for the U.S. House of Representatives. Instead, he applied unsuccessfully within his party for the nomination for election to the U.S. Senate. Since then he has worked as a doctor again. He is married to Ann Gabrill, with whom he has three children.