He has worked on several television series, including writing for Saturday Night Live and The Simpsons, adapting The Office for the United States, and co-creating Parks and Recreation and King of the Hill.

He wrote several classic episodes, including "Lisa's Wedding", "Bart Sells His Soul", and "22 Short Films About Springfield".

[4] Daniels stated that he became interested in comedy by watching Monty Python's Flying Circus as a child,[citation needed] as well as reading books by humorist S.J.

[7] Daniels and Conan O'Brien met Lorne Michaels in late 1987 and were given a three-week try-out in the Saturday Night Live writing staff.

Daniels received an Emmy nomination in the "Outstanding Individual Achievement in Music and Lyrics" category for the song "Who Needs The Kwik-E-Mart?"

[8] For season six, he wrote "Homer Badman", "Lisa's Wedding", and the "Time and Punishment" segment from "Treehouse of Horror V".

[12] His final credit for the series was for "22 Short Films About Springfield", which he served as supervising writer alongside showrunner Josh Weinstein.

[13] Daniels left The Simpsons to work on King of the Hill (another Fox show) alongside Mike Judge.

[14] Daniels rewrote the pilot script and created several important characters that did not appear in Judge's first draft (including Luanne and Cotton), as well as some characterization ideas (e.g., making Dale Gribble a conspiracy theorist).

[19] The second season was significantly better received and it was named the second best TV series of 2006 by James Poniewozik, writing that "Producer Greg Daniels created not a copy but an interpretation that sends up distinctly American work conventions ... with a tone that's more satiric and less mordant. ...

[23][24] After Amy Poehler agreed to play the lead, they decided their new series would revolve around an optimistic female bureaucrat in small-town government.

[31] The remake was picked up for a pilot, which was written by Daniels and directed by Ken Kwapis,[32] and featured Allison Janney and Tony Shalhoub as the mother and father.

In January 2019, Netflix announced that he would write and produce a new series called Space Force starring Steve Carell, who was the lead in Daniels' previous sitcom The Office.

[36] In 2021, it was announced that Daniels and King of the Hill co-creator Mike Judge had reunited to form an animation company called Bandera Entertainment,[37] to "expand the format to include as many subgenres as live-action fare."

Their first produced series was Anna Drezen's Praise Petey[38] starring Annie Murphy, John Cho, and frequent Judge collaborator Stephen Root among others.

[43] Other series in development from Daniels and Judge include an adaptation of Exploding Kittens for Netflix,[44] a reboot of King of the Hill for Hulu,[45] Zach Woods and Brandon Gardner's In the Know,[46] and Caitie Delaney and Caleb Hearon's Best Buds[47] for Peacock, Chelm: The Smartest Place on Earth with Sacha Baron Cohen for Cartoon Network and Max,[48] and Common Side Effects for Adult Swim.

[50] Daniels met Susanne Dari Lieberstein while she was Lorne Michaels' assistant at Saturday Night Live[51] and they eventually married.