The first half was a classic end-to-end thriller with both sides hitting the woodwork before Argentina opened the scoring.
Messi had linked up with PSG in August this year having spent his entire career with Barcelona at club level.
Messi joined Paris Saint-Germain in August after Barca decided not to renew the Argentinian’s contract due to La Liga’s strict salary limits.
Argentina will meet Paraguay in Asuncion on Thursday before home clashes against Uruguay and Peru on October 10 and 14, respectively.
Gaetan Laborde put Rennes ahead on the stroke of halftime after PSG star Lionel Messi had hit the crossbar with a free kick in the 31st minute.
Lionel Messi scores superb first goal for PSG in 2-0 win against Manchester City in Champions League
Lionel Messi's superb first goal for PSG was well worth the wait and delivered a timely reminder of the electric skill that has helped him win a record six Ballon d'Or trophies.
Mauricio Pochettino hopes to have Lionel Messi back in attack as the Argentine shakes off a minor knee injury that sidelined him for two games.
The Argentina star raised the bar at the Camp Nou club as he developed into one of the greatest to ever play the game before departing to join Paris Saint-Germain this year.
Pochettino dismissed any suggestion the six-time Ballon d'Or winner was unhappy, saying: "I asked him how he was and he said he was fine."
They play Manchester City next and still have to face RB Leipzig, two teams that beat PSG in last season's Champions League.
The Argentine teams up with Neymar and Kylian Mbappe as PSG coach Mauricio Pochettino lines up all three members of his all-star attack together for the first time.
After the 8-2 loss by Bayern Munich in the Champions League quarter-finals, Gerard Pique said Barcelona needed change of all kinds.
Italy's European Championship star goalkeeper, Gianluigi Donnarumma, made his debut for PSG, whose home fans must wait a while longer to see Lionel Messi at Parc des Princes.
Messi, 34, overtook Pelé's total of 77 by netting all three goals during Argentina's 3-0 win against Bolivia in World Cup qualifying. He now has 79 for the national team.
La Liga president Javier Tebas delivered some familiar broadsides on Sept 7 about PSG benefiting from state funding, followed by fresh digs against the club for signing Lionel Messi from Barcelona.