Lee Kang-in gave PSG the lead inside three minutes in Normandy only for Gautier Lloris to equalise, but late goals by Ousmane Dembele, Bradley Barcola and a Randal Kolo Muani penalty sealed the victory for the reigning French champions.
It was a comfortable win in the end for Luis Enrique's team, with their substitutes ultimately making the difference as PSG's strength in depth proved too much for a team who only just avoided relegation last season.
The French international trio of Kolo Muani, Dembele and Barcola all began the game on the bench, while Portugal midfielder Joao Neves came on at half-time for his debut after joining from Benfica for a fee that could reach 69.9 million euros ($76.7m) including bonuses.
Yet Le Havre will wonder what might have been had a Josue Casimir goal - which would have put them in front early in the second half - not been disallowed by VAR for a handball.
PSG have not made any marquee signings to fill the enormous void left by Mbappe, who departed for Madrid in June after scoring 44 goals last season and registering a club-record 256 across his seven years at the club.
It remains to be seen if Luis Enrique's team can repeat their performances of the last campaign, when they swept all the domestic honours and reached the semi-finals of the Champions League.
The Spanish coach was without several regulars here, with left-back Nuno Mendes suspended while Fabian Ruiz is not yet ready to return after helping Spain win Euro 2024.
August 16, 2024
Late goals
There was a debut on the left wing for Ibrahim Mbaye, who is only 16 and was one of three teenagers in PSG's starting line-up alongside Yoram Zague and Warren Zaire-Emery, both 18.
South Korea star Lee opened the scoring when he collected a Goncalo Ramos pass on the right wing before sending a shot into the far corner with the aid of a deflection.
However, the visitors were then dealt a blow as Ramos was forced off with an ankle injury, and his replacement Kolo Muani then sent a header crashing back off the bar.
Le Havre, in their first game under new coach Didier Digard, improved as the game went on and Abdoulaye Toure had a goal disallowed for offside just before the half-hour mark.
They were level three minutes into the second half when Lloris, the brother of former France captain Hugo, turned in Christopher Operi's free-kick. The hosts then thought they had taken the lead on 53 minutes when skipper Casimir ran through to score, but VAR ruled his effort out after a long check for a handball.
Dembele, who had been sent on for the final 20 minutes, gave PSG the advantage again on 85 minutes with a header from a Neves cross, before Barcola curled in a superb third a minute later. Kolo Muani then won and converted the late penalty which wrapped up the win for the visitors at the Stade Oceane.
Last season's runners-up Monaco face Saint-Etienne on Saturday, while Roberto De Zerbi's first game in charge of Marseille will be away to Brest, who surprisingly finished third in the last campaign.
August 16, 2024