When she joined the Writers Guild of America, West in 1975, Mason continued the legacy begun in 1953 by Helen Thompson, the Guild's first African-American member. As did Thompson, many fellow black and women writers over the years were inspired by Mason's decades-spanning career in television, film, and on the stage. Writers Guild Award-winning writer Tina Andrews notes about Mason, "So many of us are here as writers because she was there first willing to assist our journeys. I thank God I had her powerful shoulders to stand upon."

A Shreveport, Louisiana native and Grambling State University alumna, Mason began in theater, becoming a prolific playwright with her work still in production today. She penned over 25 published and produced plays such as: Living Fat, for which she won the Kennedy Center's Norman Lear Award for comedy writing at only age 19, and A Star Ain't Nothin’ but a Hole in Heaven, garnering her the first Lorraine Hansberry Playwriting Award in 1977. She also became one of the youngest playwrights – of any race – ever to be produced Off-Broadway.

She was also a successful television writer/producer. Her career in television began at barely 20 years old after being hired as a writer on the CBS hit Good Times by TV legend Norman Lear, when he was the show’s executive producer/developer. "I never saw Judy Ann Mason without a smile. She brought it to her writing and her writing brought the rest of us to laughter. She was the ultimate upper," commented Lear on Mason's passing.

Her other TV writing credits include writing or co-writing for primetime network shows such as A Different World (NBC), American Gothic (CBS), Beverly Hills 90210 (FOX), Sanford, (NBC), and the Emmy-nominated series I’ll Fly Away (NBC). Her telefilm credits include Lifetime’s Sophie & the Moonhanger (teleplay by Sara Flanigan and Judi Ann Mason, story by Sara Flanigan). In addition, she wrote on daytime serials, as Head Writer for the Writers Development Program at Guiding Light (CBS), later becoming Associate Head Writer on the ground-breaking Generations (NBC), the first daytime series to center around an African American family.