Roddick, four-time champion here at Queen's, recovered well after losing the first set, but lost his nerve towards the end of the match, allowing the world number 67 to run out a 6-4 4-6 7-5 winner in the second-round clash on centre court.
Qualifier Roger-Vasselin lost their previous meeting, but showed immense composure in the final set, successfully defending a match point against him in the 10th game.
Roddick, seeded seventh, then wilted under pressure, double-faulting to give his opponent three break points.
The Frenchman took the opportunity at the second attempt, forcing the American to net after pushing him to the baseline with a searching forehand.
Roddick, world number 32, had to break serve to stay in the match but could not do so, with Roger-Vasselin sealing the win thanks to a clever drop shot.
Roger-Vasselin will play the winner of the match between David Nalbandian and Ruben Bemelmans in the next round.