After attending law school, he started out as a law clerk for Judge John M. Walker Jr. before becoming a federal attorney, serving as assistant U.S. attorney for the United States District Court for the Southern District of New York for three years.

His mother was a lawyer and served as dean of Loyola University Chicago's law school from 1983 to 2004, where as of 2010 she continued to teach tort law,[5] and his father (who died on May 2, 2009) was professor of English at Northwestern University and an expert on Vladimir Nabokov.

Tad Friend noted: "Everyone thought it would be Conan automatically, but Rich's speech was funny and self-deprecating, in a way that was both silly and profound.

"[4] After graduation in 1985 with a degree in history and literature,[7] Appel attended Harvard Law School rather than moving into comedy, because the idea of following his mother and grandfathers into the legal profession "appealed" to him.

"[4] Appel got his first television job when David Mirkin hired him for the writing staff of The Simpsons in 1994, initially on a ten-week contract,[2] and served as a writer and producer there for four years.

[1][9] There, he wrote seven episodes, often employing the use of "joke sequences, a narrative approach to humor that eschews the quick laugh in favor of something that develops over time.

Appel was desperately trying to think of a story idea to show and decided that he had to really reach out and opted to do something about Homer's mother, who previously had only been mentioned once.

[10] Also for season seven he penned "Bart on the Road", in which he utilized the plot devices of "go to work with your parents day" and Bart getting a driving license,[12] and contributed to the episode "22 Short Films About Springfield"; the two segments he wrote for the episode (one about Marge, the other about Lionel Hutz) were both cut.

Daniels noted: "It was essential that Rich was a good writer who could deal with people, who could help manage the business in the room.

Appel then wrote and worked as a co-executive producer on The Bernie Mac Show and Kitchen Confidential,[9] and appeared as Josh in the 2004 film I Heart Huckabees.

[25] Appel co-created, alongside Mike Henry and Seth MacFarlane, the Family Guy spin-off The Cleveland Show, which they began discussing in 2007 and which premiered September 27, 2009.

[29] Starting with the sixteenth season, Appel would begin showrunning Family Guy, alongside Alec Sulkin.