Bonnie Bartlett's formative years were spent in Moline, Illinois, where her father, E.E., a erstwhile Shakespearean actor turned insurance salesman, and her mother, Carrie, a dedicated homemaker, instilled in her a passion for the performing arts. As a young woman, Bonnie became resolute in her determination to fulfill her father's unrealized dreams of acting stardom. She enrolled at Northwestern University, where she honed her craft under the guidance of esteemed instructors, and it was during her freshman year that she crossed paths with fellow thespian and future husband, William Daniels.
Following their graduation, Bonnie and William settled in New York, where they sought to make a name for themselves in the competitive world of acting. Bonnie furthered her studies under the tutelage of the renowned Lee Strasberg and initially supported herself and her husband through her early career.
In the 1950s, Bonnie landed a recurring role on the CBS soap opera Love of Life, playing the character of Vanessa Raven, a part she would go on to play for four years. The couple's first child was born in 1961, but tragically, the infant passed away within 24 hours due to complications at birth. This devastating loss prompted Bonnie and William to adopt two children later, son Michael, born in 1964, who would go on to become an assistant director and stage manager in Los Angeles, and son Robert, born in 1966, an artist and computer graphics designer in New York City.
Throughout the 1970s, Bonnie dedicated herself to her family, acting only sporadically in recurring roles, but she rekindled her passion for acting in the early 1980s, most notably in the hit TV series St. Elsewhere, and later in a recurring role in Boy Meets World.