Goalkeeper Sergio Rico made a rare appearance for PSG, who kept the front four from the 4-0 win over Montpellier in Mauro Icardi, Angel Di Maria, Kylian Mbappe and Neymar Junior.
An early scare had the home side firing a shot from a promising angle by Armand Lauriente against the side-netting after the defence were caught napping.
Lorient's early forays were duly rewarded in the last nine minutes of the first half through a smart finish from Laurent Abergel with the visitors found wanting.
The Parisans however drew level on the stroke of halftime when Neymar drilled a low shot from the spot after having gone down in the area past goalkeeper Matthieu Dreyer.
No changes from the visitors showed after the break, but Thomas Monconduit was sacrificed for Trevoh Chalobah on the side of the hosts.
PSG went ahead for the first time in the match following 58 minutes as Neymar stepped up from the spot to beat Dreyer for the second time following a foul on Icardi by Chalobah.
A third was on the cards for the league champions in the final stages after a cross into the area from Neymar met Icardi, but Dreyer smothered fantastically.
Lorient pulled the rabbit out of the hat ten minutes from time as an exchange of passes near the area allowed Yoane Wissa to profit from close-range.
The Parisans were left heartbroken at the death after Terem Moffi latched onto a long ball from Abergel to race through and beat Rico with a composed finish, as the contest concluded.