[5] As a child, she was given the nickname Bud due to her being a tomboy and refusing to wear dresses, which gave her the name Rosebud.

Baker's father was mostly absent in her life and emotionally distant due to his work, while her mother was a painter.

[2] Baker attended Langley High School, where she received mostly poor grades and was briefly a cheerleader before getting suspended from the squad.

In June 2002, her 7-year-old sister, Graeme,[a] drowned after becoming caught in a hot tub drain during Baker's outdoor graduation party in McLean.

[6] Baker received a Bachelor of Arts in acting at Emerson College in 2006,[8] where she also became severely alcoholic and depressed as a result of grief from the death of her sister, which she compared to "getting very old quickly".

In 2014, Baker did stand-up for the first time during an open-mic night at a comedy club in Austin, Texas while on a cross-country road trip with a childhood friend.

[2][16][17] Baker became a writer for Saturday Night Live during its 47th season in February 2022, and appeared in a recurring role on Hulu's comedy-drama series Life & Beth in March 2022.