Jones will take over the captaincy at Gloucestershire from Australian Michael Klinger in the County Championship and will be used as a specialist batsman.
"I'd like to thank Kent for the fantastic 15 seasons I spent with them," Jones told the club's official website.
"Following an enjoyable month with Gloucestershire during 2014, I am excited to be joining the club and for the challenges that lie ahead.
"This is a young and talented squad and I relish the opportunity of working with them and to playing a part in their development."
Jones was part of the England team that won The Ashes in 2005.