Iniesta signed the new deal on Monday which will keep him at the Nou Camp until June 2018, with the contract set to automatically renew from 2017/18 provided he has played in a certain number of matches the season prior.
The 29-year-old's previous deal had been due to expire in 2015, and if he stays until the end of the new arrangement he will be 34 and have spent 22 years at the Catalan club.
Iniesta spoke of his intentions for the future following Sunday's 5-2 win over Getafe.
"It will be a good day, it's possible for me to retire at Barca," Iniesta told fcbarcelona.com.
"I hope to stay healthy and help the team win titles at the end of the season.
"We're confident. Next year we have to follow the same path and get to April and May in a position to fight for all the titles."
Pedro scored a hat-trick in the space of eight minutes as Barcelona came from two goals down to beat Getafe and return to the top of the Primera Division in time for Christmas.
A much-changed Barca side, without the suspended Neymar plus the injured trio of Xavi, Lionel Messi and goalkeeper Victor Valdes, conceded twice in the opening quarter of an hour, Sergio Escudero breaking the deadlock and then Lisandro Lopez scoring a header.
But Pedro's stunning burst of scoring was followed by a volley and a penalty from Cesc Fabregas in the second half - with Pedro getting an assist and then winning the spot-kick to crown a brilliant individual performance.
Jordi Alba was another of the stand-out players in the match and set up Pedro for one of the forward's three goals.
The 24-year-old admitted a lack in concentration was Barca's downfall early in the match.
"We conceded two goals because we were relaxed, but the team reacted and we ended up playing a good game," Alba said.
"In general we played a good game. We're happy that we ended the year as league leaders, we got an important victory."