The 24-year-old made her 13th appearance this season and scored her side's second goal of the match to ease relegation fears for Sarah M'Barek's ladies at the Stade de l'Europe.
Having missed scoring chances in the first half, Suzy Morin broke the deadlock in the 62nd minute before Oparanozie double the lead two minutes later.
In the 70th minute, Clara Njoiran pulled one back for Rodex but 11 minutes later Faustine Robert restored the hosts' two-goal lead to seal their victory.
The Nigeria striker's goal was her fourth in 14 games for Guingamp in all competitons. The victory moves them out of the drop zone to the eighth position with 12 points from 13 games.
They will face second-placed Paris Saint-Germain in their next league encounter - a week after French Women Cup clash with CBOS Angers on Sunday, January 28.