Bergman was born in Los Angeles, California. Her parents were Jewish, but Bergman was non-practicing and converted to Roman Catholicism after exploring several Christian denominations; although she still remained proud of her Jewish heritage. At an early age, she found herself drawn to fantasy entertainment ranging from science fiction to anything Disney. She was always proud of the fact that as a child she and her mother wrote letters to NBC to help keep the original Star Trek on the air for a third season. With regard to Disney, she regularly visited Disneyland and was once quoted as saying, "My one regret is that I never got to meet Walt Disney." Later, with her husband, Dino Andrade, she enjoyed Star Trek conventions while continuing to visit Disneyland, Walt Disney World and Disneyland Paris.
Before her death, Bergman was good friends with fellow actress Tara Strong, her co-star in Scooby-Doo on Zombie Island. Nine months before her death, Bergman gave Strong a pet dog, whom she named Abbey, as a 26th birthday gift.
Bergman was known for voicing most of the female characters in animated series such as Fox Kids' The Secret Files of the Spy Dogs, in which she played a dog named Mitzy and also a number of other characters. She also voiced characters for South Park and the 1999 feature film South Park: Bigger, Longer & Uncut. Her characters included Liane Cartman, Sheila Broflovski, Sharon Marsh, Mrs. McCormick and Wendy Testaburger. Originally, Bergman was credited on South Park as Shannen Cassidy because she was also serving as Disney's official Snow White voice. The South Park episode "Mr. Hankey's Christmas Classics" was dedicated to her, as was the episode "Starvin' Marvin in Space," the first episode to air after her death.
Bergman's other voice credits included over 400 television commercials, including the voice of Mrs. Butterworth in Mrs. Butterworth's syrup commercials, as well as various Disney films (Beauty and the Beast, The Hunchback of Notre Dame, Hercules, Mulan, Toy Story 2), video games including The Curse of Monkey Island and the English version of Tenchu 2: Birth of the Stealth Assassins, Jay Jay the Jet Plane, Timmy Turner in Oh Yeah! Cartoons, episodes of The Fairly OddParents (when the pilot episodes were aired as actual episodes in 2001, Bergman's voice was overdubbed by Tara Strong) and several female voices in The Tick animated series. She also contributed vocals to the "Weird Al" Yankovic song "Pretty Fly for a Rabbi", alongside Tress MacNeille. According to the IMDb, her final film role was in Balto II: Wolf Quest.
Bergman also carried on the Scooby Doo character Daphne Blake in the following movies: Scooby-Doo on Zombie Island in 1998, Scooby-Doo and the Witch's Ghost in 1999 and Scooby-Doo and the Alien Invaders in 2000, this last one being a posthumous dedicatory to her.
After suffering from depression and anxiety, Bergman committed suicide by shooting herself with a 12 gauge shotgun  in her West Los Angeles, California apartment at the age of 38, on November 11, 1999. Andrade, along with a friend, discovered her body and suicide note and later established the Mary Kay Bergman Memorial Fund, which contributes to the operation of the Suicide Prevention Center at the Didi Hirsch Community Mental Health Center. She is interred at Forest Lawn Memorial Park (Hollywood Hills)
After Bergman's death, voice actresses Eliza Schneider and Mona Marshall took over all of her voice roles on South Park. Grey DeLisle replaced Bergman as Daphne Blake in Scooby-Doo and the Cyber Chase. Good friend Tara Strong also took over her voice role of Batgirl in Batman: The Animated Series (Bergman had previously voiced the character in the movie SubZero).
- "A Conversation With... Dino Andrade". Mary Kay Bergman memorial. 2000. Retrieved 2006-12-13.
- "The Death of Mary Kay Bergman" Retrieved 2010-07-01.
- "A Conversation With... Dino Andrade". Mary Kay Bergman memorial. 2000. Retrieved 2007-10-05.
- "Official obituary". Mary Kay Bergman memorial. 2000. Retrieved 2007-10-05.
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|Daphne Blake voice
|South Park lead female voice
Eliza Schneider and Mona Marshall