MacKenzie Scott Tuttle was born on April 7, 1970, in San Francisco, California. Her father was a financial planner. In 1988, she graduated from Hotchkiss School in Lakeville, Connecticut. Tuttle earned her bachelor’s degree in English at Princeton University with highest honors in 1992. She studied under writer Toni Morrison, who said Tuttle was “one of the best students I’ve ever had” in her creative writing classes.

MacKenzie was married to Jeff Bezos, founder of Amazon and Blue Origin, from 1993 to 2019. She met him while working as his assistant at D. E. Shaw in 1992; after three months of dating in New York they married and moved to Seattle, Washington in 1994. They have four children: three sons and one daughter adopted from China. Their communal property divorce in 2019 left MacKenzie with US$35.6 billion in Amazon stock while her ex-husband retained 75% of the couple’s Amazon stock. She became the third-wealthiest woman in the world and one of the wealthiest people overall in April 2019. MacKenzie kept her last name instead of reverting to her maiden name, Tuttle, but later began going by the name MacKenzie Scott, with the surname derived from her middle name.

After graduating, she worked for D. E. Shaw, a quantitative hedge fund in New York, as a recruiter and a writer from 1992 to 1994. There, she worked for Jeff Bezos, then a senior vice-president, as a research associate. MacKenzie wrote her debut novel, The Testing of Luther Albright, eleven years later in 2005 for which she won an American Book Award in 2006. Her second novel, Traps, was published in 2013.

In 2014, MacKenzie founded Bystander Revolution, an anti-bullying organization, where she serves as executive director.

In May 2019, she signed the Giving Pledge, a charitable giving campaign in which she willingly committed to give away most her wealth to charity over her lifetime or in her will, though her pledge is legally non-binding. Within a year of joining the Giving Pledge, Scott had donated $1.7 billion to 116 non-profit organizations, with a focus on racial equality, LGBTQ+ equality, democracy, and climate change.