Twenty-one year-old Dimitrov has been branded 'Baby Fed' due to comparisons between he and Roger Federer, and the six-time Wimbledon champions would have been impressed with some of the Bulgarian's powerful groundstrokes he displayed at Queen's.
Mahut was being tipped for a tilt at the title here after beating defending champions Murray, but the world number 65 had no answer to the power of the Bulgarian, who recorded a 7-6 (7/3) 6-4 win.
Mahut flew out of the blocks, breaking Dimitrov early on, but he started to get complacent with his groundstrokes.
The Frenchman handed Dimitrov two break points almost immediately but the Bulgarian wasted both opportunities and Mahut retained his advantage.
A topsy turvy 10th game saw Mahut waste one set point, and Dimitrov spurn six break points, before he finally broke the Frenchman with a powerful backhand.
Mahut played flawlessly against Murray in his third-set tie break on Wednesday but he allowed Dimitrov to break in with a clever lob and he wrapped up the set with a drop volley after just over an hour's play on centre court.
Mahut seemed to have lost his edge and could not provide any response to the Federer-esque forehands Dimitrov was powering down from the baseline.
Mahut clipped the net cord and the ball went long to allow Dimitrov to break and move 3-1 in the second and the Bulgarian would have further extended his lead in his following service game.
Dimitrov already had the break he needed, however, and he held his next two games to love to ease in to the quarter-finals where he will meet ninth seed Kevin Anderson.
Anderson overcame fifth seed Feliciano Lopez 7-6 (12/10) 7-6 (9/7) on court one.