Memphis Depay ignited the goals surge when he opened scoring for the Kids 10 minutes into the encounter.
Five minutes later, Alain Casanova’s men levelled proceedings through Matthieu Dossevi before Traore restored the lead to the Groupama Stadium outfit at the half-hour mark.
In the 35th minute, Nabil Fekir scored from the penalty spot to wrap up a commanding first-half display.
Dembele who made his 22nd league appearance in the tie then found the back of the net in the 67th minute and completed his brace three minutes later to take his goals tally to nine this season.
The visitors suffered another setback when Yannick Cahuzac was shown a straight red card.
Former Celtic forward Dembele featured for 79 minutes before making way for Yassin Fekir while Traore was replaced by Martin Terrier six minutes before time.
Despite the emphatic win, Bruno Genesio’s men remain in the third spot in the log with 49 points from 27games.
Both African stars will hope to continue with their sterling performances when Lyon visit Strasbourg on March 9.