Newman was part of the original cast of NBC's sketch comedy series Saturday Night Live from its inception in 1975 until her departure in 1980.

The next year Newman became one of the original cast members of Saturday Night Live, working there from 1975 to 1980 and creating characters Connie Conehead, proto-Valley girl Sherry, and Christie Christina.

[10] By the age of 19, Newman returned to the United States, and moved to Los Angeles, where she did a brief stint at a secretarial school.

"[12] In 1974, Lorne Michaels hired 22-year-old Newman for a Lily Tomlin special, impressed with her work as founder and original member of The Groundlings.

[15] Newman admits that she was "never a good improviser," but when in character, like an angry Jewish poet, a flight attendant, an eccentric chef, or a British groupie, she was "free".

Commenting on her early experiences during Saturday Night Live she said: "When I first performed (my characters) and the audience responded, I felt like crying, I mean the idea that what I saw—what other people saw—(meant) I wasn't so alone in my perspective.

"[18] Newman is best known for her roles as Connie Conehead, proto-Valley girl Sherry, and Christie Christina, the ditzy co-host of E. Buzz Miller (Dan Aykroyd)'s public-access television cable TV show.

Using her own name, Newman also played a TV news reporter for Weekend Update when the segment was hosted by Chevy Chase (1975–1976) and Jane Curtin (1976–1980).

In her memoirs, Newman recounted dating Dan Aykroyd, Warren Zevon, Peter Cook, Phil Hartman, and P.J.

Prior to leaving SNL, Newman appeared in American Hot Wax (1978) and did a cameo in Mr. Mike's Mondo Video (1979).

In 1986 she starred in the syndicated B-movie comedy series, The Canned Film Festival, playing the lead role as Laraine the usherette.

Newman celebrated her 36th birthday in March 1988 with a party in Los Angeles that was the last time Gilda Radner was with her original SNL co-stars.

In the 2000s Newman lent her voice to animated movie and TV characters in Danny Phantom, As Told By Ginger, Avatar: The Last Airbender, Metalocalypse and Jimmy Neutron: Boy Genius.

She provided voice work for WALL-E, Battle for Terra, Ponyo, Jungle Junction, Cars, Up!, Finding Nemo, Monsters, Inc., Barnyard, Cloudy with a Chance of Meatballs, Happily N'Ever After, and Horton Hears a Who!.

In 2017, the original cast of Saturday Night Live (including Newman) was inducted into the Television Academy Hall of Fame.

[25][21] Newman has been nominated for awards numerous times, most notably for an Emmy in 1979 as a cast member of Saturday Night Live.