Project Runway Season 3 was the third season of Project Runway, Bravo's successful reality competition for fashion designers. The third season of the show, with Heidi Klum returning as the host and Tim Gunn as the designers' guide, began airing on July 12, 2006. This broke tradition from the previous two seasons, which premiered in December, with the finales taking place at Olympus Fashion Week in February.

Season 3 brought in a new set of sponsors, notably Macy's replacing Banana Republic. NBC re-aired the first two episodes of Project Runway 3 five days after their original Bravo airings. The third season also introduced live viewer poll questions. During the second half-hour of the first airing of each episode, Bravo posed a question to viewers pertaining to the current episode. Viewers could answer through the BravoTV.com website or through cell phone text message.

The winner, Jeffrey Sebelia, received a spread in Elle magazine, a mentorship with INC (Inter-National Concepts) Design, a year of representation by Designers Management Agency, a 2007 Saturn Sky Roadster, and $100,000 to start a clothing line (furnished by TRESemmé haircare).