Goals from the Argentine, Zlatan Ibrahimovic and an own goal by Gary Kagelmacher extended the Parisians' lead at the top to eight points in Ligue 1
Ezequiel Lavezzi, whose uncle was shot dead earlier this week, opened the scoring with a predatory finish after Zlatan Ibrahimovic's free kick had been deflected into his path.
In the second period the hosts added to their lead, with the Swede volleying home before a Gary Kagelmacher put the home side firmly in control.
The defeat is Valenciennes' 14th of the Ligue 1 season and leaves the side in the bottom three.
PSG, who gave a first start to Yohan Cabaye, started with real attacking intent and should have been two goals ahead inside the opening 10 minutes as Valenciennes struggled to contain them.
Ibrahimovic saw a flicked effort cleared off the line by Kagelmacher in the fourth minute and Nicolas Penneteau then made a fine save to deny Thiago Silva five minutes later.
With pressure beginning to build on the Valenciennes' goal, it was unsurprising that PSG's bright start paid dividends as Lavezzi plundered his fourth goal of the season in the 18th minute.
An Ibrahimovic free kick squeezed through the wall and dropped at the feet of the Argentine, who calmly fired low past Penneteau from eight yards.
The 28-year-old could have had a hat-trick before the half hour, but he wasted two excellent chances, while Lucas Digne saw a low shot go just wide.
Valenciennes' only sight of goal in the first half came in the 31st minute as PSG failed to clear a left-wing cross, the ball fell to David Ducourtioux, but he dragged his shot wide after controlling the ball with his chest.
Ibrahimovic, having been denied in the first half, got his goal five minutes into the second period after some slack defending from the visitors.
Having failed to clear Digne's cross, Valenciennes allowed Menez the chance to volley towards goal. He failed to connect properly, but the ball bounced to the Sweden international and he nonchalantly fired home his 19th league goal of the season from 12 yards.
It was 3-0 two minutes later as Kagelmacher got himself into a tangle trying to clear Menez's cross and the Uruguayan inadvertently turned the ball into his own goal.
With the game won, Blanc began to think about the first leg of PSG's Champions League tie with Leverkusen on Tuesday as Ibrahimovic, Lavezzi and Thiago Motta were all substituted as the hosts coasted to victory.