She is best known for her extensive work in animation, voicing characters such as Elmyra Duff in Tiny Toon Adventures and related media, Susie Carmichael in Rugrats and Lizard in Spirit Rangers, for which she won a NAACP Image Awards and received two nominations at the Children's and Family Emmy Awards.

Summer's acting career began in 1983 when she was cast as Penny in the first season of the original version of Inspector Gadget.

In the fall of that same year, Summer and her A Different World co-star Jenifer Lewis starred in the prime time drama Courthouse, which was cancelled two months after it premiered.

[9] Apart from guest appearances on other live-action television shows such as Living Single, Better Things, and The Fresh Prince of Bel-Air, Summer's professional work since has mostly been limited to voice acting.

[10] At the start of the third season of A Different World in 1988, the cartoon series The Real Ghostbusters episodes were expanded from their original half-hour format to an hour.

In these lighter episodes, she voiced Chilly Cooper, the neighborhood ice-cream woman and innocent love interest of Slimer.

Among her most famous roles was in Inspector Gadget (Season 1) as Penny (a role she reprised in the Robot Chicken episode "Adoption's an Option"), WB's Tiny Toon Adventures (1990) as Elmyra Duff (which she reprised for Pinky, Elmyra & the Brain) and Mary Melody, Aka Pella in WB's Histeria!, Susie Carmichael in Nickelodeon's Rugrats and its spin-off All Grown Up!, Cleo the Poodle in PBS Kids' Clifford the Big Red Dog, Miranda from Nickelodeon's As Told by Ginger, Foxxy Love in Drawn Together, Dulcy the Dragon in Sonic the Hedgehog, Valerie Gray in Nickelodeon's Danny Phantom, Numbuh 5 and Cree Lincoln in Cartoon Network's Codename: Kids Next Door, Penelope in Barbie as Rapunzel, octogenarian villain Granny May on WordGirl, Tiff from Nickelodeon's My Life as a Teenage Robot, and Blackarachnia in Transformers: Animated.

Summer has a recurring guest role as librarian Rosalyn Inez on Season 3 of ABC sitcom Abbott Elementary.

[14] She performed voice over for the games Baldur's Gate: Dark Alliance, Black, as well as Tony Hawk's American Wasteland.

She was the voice of Tandi in Fallout and First Citizen Lynette in Fallout 2, Tatjana in Arc the Lad: Twilight of the Spirits, Lady Belgemine, Young Tidus and additional voice-overs in Final Fantasy X, Lenne/Calli in Final Fantasy X-2, Storm in Marvel Super Hero Squad, Cynder in The Legend of Spyro: A New Beginning, Magma in X-Men Legends, and the Inca Princess Micay in Pitfall: The Lost Expedition.

The character of Foxxy Love in Drawn Together was a singer, with songs like "La-La-La-La-Labia" and "Crashy Smashy", Numbuh 5 from Codename: Kids Next Door sang a lullaby to lull babies to sleep.

She provided the voice of a recurring pomegranate singer in The High Fructose Adventures of Annoying Orange, who usually sang during montage sequences.