Smigel first established himself as a writer on Saturday Night Live by joining the writing staff when Lorne Michaels returned as executive producer for the 1985–1986 season.

This is when Smigel began to write more memorable sketches, including one where host William Shatner urged worshipful attendees at a Star Trek convention to "get a life."

Smigel rarely appeared on screen, though he was credited as a featured player in the early 1990s and played a recurring character in the Bill Swerski's Superfans sketches.

[9] Upon the show's cancellation, Smigel continued developing more cartoon ideas the following summer and would begin airing them on Saturday Night Live under the TV Funhouse banner.

"[10] Smigel's most famous creation, however, would be the foul-mouthed puppet Triumph the Insult Comic Dog, who mercilessly mocks celebrities and others in the style of a Borscht Belt comedian.

Smigel continued to establish himself on Saturday Night Live by producing short animated segments under the title TV Funhouse, which usually satirizes public figures and popular culture.

[11] Additionally, Smigel played a gay mailman in the Adam Sandler film I Now Pronounce You Chuck and Larry and Yari the Mechanic in the "Mister Softee" episode of Curb Your Enthusiasm.

[13] In September 2020, after being brought on to develop the project in 2019, Fox announced that Smigel would executive produce Let's Be Real — a one-off adaptation of the French satirical series Les Guignols.

[16] Stephen Colbert addressed the incident in his monologue, stating that Smigel had committed "First-Degree Puppetry" and that "Drawing any equivalence between rioters storming our Capitol to prevent the counting of electoral ballots and a cigar-chomping toy dog is a shameful and grotesque insult to the memory of everyone who died.” The United States Capitol Police released a statement saying that “This is an active criminal investigation, and may result in additional criminal charges after consultation with the U.S. Attorney.”[17] On July 19, it was announced no charges would be filed.

[18] Smigel met his wife, Michelle, when she worked as a lighting technician for the theater in Chicago where he performed as part of the comedy troupe "All You Can Eat and the Temple of Dooom".