Barton, who has also played for Newcastle United, Queens Park Rangers and Burnley, as well as Scottish side Rangers, was banned from football for 18 months after admitting to placing 1,260 bets between March 26, 2006 and May 13, 2016.
His ban was reduced to 13 months on appeal and will end on June 1.
"My first job in management was always going to be a big decision for me and I'm delighted with the opportunity ahead, I'm joining a club with big ambitions," Barton said in a statement on the club website.
Fleetwood chairman Andy Pilley said Barton had the potential to become one of the best in the new generation of coaches.
"He's someone I've known for a number of years and I'm convinced he's ready to make the step into management, and that he will be a huge success," Pilley added.
(Reporting by Simon Jennings in Bengaluru; Editing by Christian Radnedge)
