It was the away side who started the better and they might have led after just two minutes with an effort from Nene, but it drifted just wide.
Valenciennes took the lead, however, after just eight minutes when Vincent Aboubakar struck from close range. It was quickly two, three minutes later, when Remi Gomis found the bottom corner from outside the box.
PSG had a goal back seconds later when Nene converted from close range after smart work from Jeremy Menez.
Alex might have levelled the score with an effort after 30 minutes, but his free kick just drifted wide of the target.
PSG were level at 2-2 moments before the break, however, when Maxwell found the bottom corner from a difficult angle to level up proceedings.
Menez made it 4-2 to PSG after 58 minutes with a fine strike to complete a quite stunning comeback from Carlo Ancelotti's side.
Chances continued to fall for PSG in the latter stages of the match, but it was Valenciennes who added the seventh goal of the match via Renaud Cohade, who struck a free kick into the top corner.
PSG held on, however, to move the club into pole position for the Ligue 1 title.