[2] After graduating, Kitsis and Horowitz traveled together to Los Angeles, and worked together on Fantasy Island, Felicity and Popular, before joining the Lost team halfway through the first season.

Horowitz, Kitsis and the Lost writing staff won the Writers Guild of America (WGA) Award for Best Dramatic Series at the February 2006 ceremony for their work on the first and second seasons.

[11] In December 2019, it was announced that Horowitz and Kitsis were working on a new TV show set in the world of fairy tales and Disney titled Epic.

[13] Kitsis and Horowitz worked as writers on early unused drafts of the Universal project Ouija,[14] and co-wrote the film Tron: Legacy in 2010.

[15] He frequently collaborates with a tightly knit group of film professionals which include J. J. Abrams, Damon Lindelof, Alex Kurtzman, Roberto Orci, Edward Kitsis, Andre Nemec, Josh Appelbaum, Jeff Pinkner, and Bryan Burk.