Neymar scored the opener and crossed for Marquinhos to head in the champions' second as they responded well to their 2-1 home loss to Manchester City in the Champions League this week.
With Kylian Mbappe missing through injury and Marco Verratti, Angel Di Maria and Ander Herrera starting on the bench, PSG were made to work hard for a result that lifted them back above Lille at the summit, at the very least for a few hours.
Ignatius Ganago pulled a goal back for European hopefuls Lens, but Mauricio Pochettino's men held firm for a morale-boosting win ahead of their second-leg clash with City in England next Tuesday.
PSG, who lost right-back Colin Dagba to injury before the 20-minute mark, had few early chances despite their dominance, although Danilo Pereira tested Wuilker Farinez with a powerful header that was well saved by the Lens keeper.
Lens had done well to keep Neymar quiet but gifted him the opener 32 minutes in, the Brazil star slotting home confidently after Julian Draxler had pinched possession from Facundo Medina on the edge of the box.
Pablo Sarabia should have scored a second after Neymar's header from a fine Marquinhos pass, but Farinez produced a superb one-handed stop, and Lens could have snatched an equaliser before half-time had Jonathan Clauss and Clement Michelin shown more composure inside the box.
Lens began the second half well but PSG doubled their lead just before the hour mark, Marquinhos rising unchallenged to head in Neymar's corner from the right.
However, the visitors halved the deficit barely two minutes later, Ganago hooking the ball through Navas' legs after Arnaud Kalimuendo sliced an attempted overhead kick.
Neymar curled a free-kick off the right post, seemingly via the fingertips of Farinez, and Mauro Icardi saw a goal disallowed for a Marco Verratti offside, but Lens could not capitalise on those moments of fortune.