Toulouse were made to pay for their failure to turn possession into goals at the Stadium Municipal as first-half strikes from Alharbi El Jadeyaoui and Benjamin Bourigeaud helped Antoine Kombouare's men to a timely three points.
Wissam Ben Yedder had a goal ruled out for Toulouse after the break, while the visitors had goalkeeper Valentin Belon to thank for a string of fine saves.
It took just 11 minutes for the opening goal to arrive. Deme N'Diaye found space down the left and his cross was stabbed home by the outstretched foot of El Jadeyaoui.
Seeking a swift response, Toulouse pushed hard for an equaliser and Oscar Trejo forced a smart stop from Belon.
Lens doubled their lead just before the half-hour mark, somewhat against the run of play, when the ball fell kindly for Bourigeaud, who swept home from 10 yards.
Unsurprisingly, it was Toulouse who asked most of the questions after the break and Lens had Belon to thank for maintaining their two-goal lead when he made an outstanding fingertip save from Aleksandar Pesic's firm header.
Ben Yedder did have the ball in the goal for Toulouse on 65 minutes, but the referee's assistant flagged for a foul by Pesic in the build-up, the decision seemingly a harsh one.
Belon then received more pats on the back from his team-mates when he kept out substitute Martin Braithwaite's low drive when one-on-one.
Lens' victory sees them move off the foot of the table to 14th in the Ligue 1 standings, while Toulouse have now lost consecutive league matches.
