Jagielka, who will turn 37 years of age a week into the 2019/20 Premier League season, was reduced to a fringe role this season after playing just seven times and starting only four games.
Clarifying the situation on social media, Jagielka explained: "It's been hard to confirm my situation for next season as that decision hadn't been fully made by the club until now, unfortunately my journey at Everton has come to an end after 12 fantastic seasons.
"I have been lucky enough to play over 380 games and lucky enough to be club captain for 6 years. All I can say is thanks to all the players I've played alongside, all the staff that have helped me in their own way, the chairman and of course the amazing fans.
"Wishing everyone associated with this special clubs the very best for the future!"
Manchester-born Jagielka joined Everton from Sheffield United in the summer of 2007 and was immediately a regular in David Moyes' Toffees team.
He helped the club to consecutive fifth place Premier League finishes in 2007/08 and 2008/09 and was even named Premier League Player of the Month in February of the latter.
On top of that, the player converted the winning penalty in the FA Cup semi final shootout against Manchester United at Wembley that season, but was cruelly ruled out of the final against Chelsea when he suffered knee ligament damage soon afterwards.
Jagielka was also named Everton Player of the Year in 2008/09 and 2014/15.
It remains to be seen what the next stage of his career might be.
Source : 90min