Lieber is credited on the films Tuck Everlasting and Tangled, as well as having been creator/executive producer for unaired TV pilots for Fox Broadcasting Company (2004) and Sony Television in (2008).

ABC hired Lieber, based on his pitch with studio Spelling Television, to write a pilot for Lost.

As the project developed, ABC soured on the direction they had given Lieber, and approached J. J. Abrams and Damon Lindelof, who had an overall deal with their own studio, to rewrite.

[2][3] An industry-standard arbitration was triggered by the competing drafts and the Writers Guild of America (WGA) ultimately recognized Lieber as co-creator of the show (Lieber shares story credit with Abrams and Lindelof on the pilot).

Lieber 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.