Laurent Blanc's men moved to the top of Ligue 1, with second-placed Lyon not in action until Sunday
The striker had missed the previous two games due to suspension but made his return for a much-changed PSG side, which saw captain Thiago Silva left out of the squad at the Parc des Princes.
Coach Laurent Blanc had described the meeting with relegation-threatened Lens as a "tune up" for Ibrahimovic ahead of their Champions League last 16 second-leg clash with Chelsea on Wednesday.
And that proved to be the case as PSG made relatively short work of Antoine Kombouare's men, with the Sweden star squandering a number of first-half opportunities before David Luiz broke the deadlock with a long-range free-kick.
Ibrahimovic coolly converted from 12 yards on the hour mark, with late goals from Blaise Matuidi and Javier Pastore applying gloss to the scoreline after Yoann Touzghar had pulled one back.
PSG's win means they have now put the pressure firmly on Lyon, who visit Montpellier on Sunday.
The hosts made a quick start to proceedings and went close in the opening minute as Luiz headed over from a corner.
Jean-Christophe Bahebeck was then saved by the offside flag as he somehow hit wide from Ezequiel Lavezzi's low cross before Ibrahimovic hit the woodwork in the 14th minute.
The Sweden international lashed an effort against the crossbar after being brilliantly fed by Marco Verratti.
Lens did threaten as Pablo Chavarria drew a good save from Salvatore Sirigu shortly after Rudy Riou had kept out a Luiz header.
Blanc's men continued to waste opportunities, with Ibrahimovic surprisingly shooting straight at Riou as he attempted to lob the keeper one-on-one.
But PSG's persistence finally paid off two minutes before the interval when Luiz's 30-yard free-kick swerved into the bottom-right corner, with the unsighted Riou unable to do anything after mistakenly moving to his right.
Lavezzi should have put PSG in complete command seven minutes after the restart when he was slipped through by Verratti, however, he was denied by a brilliant challenge from Ludovic Baal after the Argentina forward had rounded Riou.
Yet Lavezzi's profligacy was rendered immaterial by Baptiste Guillaume's foul on Gregory van der Wiel on the right-hand side of the area, which allowed Ibrahimovic to step up and slot the resulting penalty into the bottom-left corner.
Lens refused to lie down, though, and pulled a goal back just eight minutes later as Touzghar beat Luiz to a low Baal delivery to prod beyond Sirigu and fray the nerves of the home fans.
Substitute Edinson Cavani was denied by a strong Riou save, shortly before fellow replacement Pastore crossed for Matuidi to turn home at the far post.
And the hosts provided one final flourish in the 82nd minute, Pastore powering home a lofted Ibrahimovic pass on the volley before Van der Wiel struck the bar as PSG ensured they will travel to Stamford Bridge in rude health.