Allison Janney was born in Boston, Massachusetts, on November 19, 1959, to a jazz musician father and a homemaker mother.

Her parents divorced when she was young, and she grew up with her mother and two brothers in Dayton, Ohio.

Janney studied drama at Kenyon College in Ohio, where she became interested in acting after performing in several plays.

After college, she moved to New York City to pursue a career in theatre and worked as a waitress and a receptionist to make ends meet. 

Janney made her Broadway debut in 1996 in the play "Present Laughter," which earned her a Tony nomination.

Janney has also done voiceover work, including in the animated movie "Finding Nemo" and the TV show "American Dad!" 

Janney has been open about her struggles with addiction and has been sober for over 20 years.

She is also an advocate for animal rights and has been involved with the organisation The Humane Society of the United States. 

Janney has never been married and has no children, but she has been in several long-term relationships with men in the entertainment industry. 

She stands at an impressive height of 6 feet tall, which has often been commented on in interviews and on red carpets.

In her free time, she enjoys playing tennis, hiking, and travelling. 

Janney has a net worth of approximately $14 million, which she has amassed through her successful acting career.