The Argentine, wearing his new number 30 PSG shirt, received a standing ovation as he replaced his friend Neymar in front of a sell-out crowd.
It was the first club game of his career for a team other than Barcelona.
Kylian Mbappe scored both goals on what could be his final appearance for the club,
with Real Madrid keen to sign him before Tuesday’s transfer deadline.
Real Madrid have made a 160m euro (£137m) bid to sign the 22-year-old, who has now scored 135 goals in 175 games for PSG.
His first goal was a header from an Angel di Maria cross and for his second he swept home Achraf Hakimi’s cross.
But the headlines will be about 34-year-old Messi, who came on moments after that second goal.
Tickets for the game were being resold for about 6,000 euros after Reims sold over,
20,000 tickets for the Stade Auguste-Delaune match. Before Messi’s signing only about 6,000 had been sold.
Their purchasers may have been disappointed to see Messi only named on,
the bench – although he got an ovation as he warmed up, with fans chanting his name, and an even bigger one when he came on.
He played some nice passes and was involved in good link-up play, drawing several fouls.
However he had few touches in the penalty area and no shooting opportunities.
Messi had missed the first few games for PSG since his free transfer move following his exit from Barcelona.
This was his first game since winning the Copa America with Argentina in July.
He joined Barcelona as a 13-year-old and scored a record 672 goals in 778 games for the club.
He has won six Ballons d’Or – also a record – and is considered one of the greatest footballers ever.
Much more to be expecting from the Argentine Star after the international break.