The Spain international, 33, came through the youth system with the club and turned professional in 2001.
He has enjoyed a glittering career for club and country, and said: “This is my last season here.”
Iniesta’s emotional press conference was witnessed by a number of members of the Barca first team.
He has won eight La Liga titles with the club and four Champions Leagues, and scored the only goal as Spain beat Holland to win the 2010 World Cup in South Africa.
“I want to thank my team-mates,” he said.
Iniesta has been linked with a move to the Chinese Super League when his time at Barcelona ends.
Asked about his future, Iniesta added: “There are still things to be sorted. I have said I will never play against Barca, so I won’t play in Europe. Barca has given me everything.”
Iniesta continued: “My only aim was to be a success at this club and I have done that.”
He said never winning the Ballon d’Or was not something he regretted and added: “The magic I’ve been through as a player is enough for me, that’s what I have gained happiness from.”
More to follow…