Iniesta completed 83 minutes and looked back to his best against last season's Champions League finalists, supplying the assist for Lionel Messi's second as the home side began Group D on a winning note.
The veteran playmaker has re-established his place as an important cog under new boss Ernesto Valverde following a campaign blighted by niggling injuries last season.
Iniesta, who started in both of Spain's World Cup qualifiers over the international break, made just 23 league appearances under Luis Enrique last term, his lowest tally since breaking into the starting XI in 2004-05.
"I am happy to have started the competition with a win and feeling good against an always tough opponent," said Iniesta in quotes tweeted by Barca.
He added to TV3: "With Luis Enrique, the way he had to manage it was shared.
"The coach always wants what is best for the club. The important thing is to train well and to have no setback."
Barca's next Champions League assignment is a trip to Portuguese heavyweights Sporting, who beat Olympiacos 3-2 on Tuesday.