The third season of the American serial drama television series Lost commenced airing in the United States and Canada on October 4, 2006, and concluded on May 23, 2007.

[1] In response to fan complaints about scheduling in the previous seasons, ABC decided to air the episodes without reruns, albeit in two separate blocks.

[6] The season was produced by Touchstone Television (now ABC Studios), Bad Robot and Grass Skirt Productions and was aired on the American Broadcasting Company network in the United States of America.

Down the stretch, critics lauded Lost for one powerhouse episode after another, satisfying frustrated viewers by providing long-sought answers to some mysteries while simultaneously igniting strong new plotlines.

The website's critical consensus reads, "Lost asks its audience to suspend their disbelief in ways that can be extremely trying for the grounded sci-fi show, but its character-driven plot holds season three together.

Reaction to two new characters, Nikki and Paulo, was generally negative, with Lindelof even acknowledging that the couple was "universally despised" by fans.

[38] "Flashes Before Your Eyes", written by Damon Lindelof and Drew Goddard, was nominated for a Writers Guild of America Award in the "Episodic Drama" category.

[42] The season also received two Directors Guild Award nominations, Eric Laneuville for "The Brig" and Jack Bender for "Through the Looking Glass".

[43] The season averaged 13.74 million American viewers per episode, ranking 17th in viewership and ninth in the key adults 18–49 demographic.