Theirs is an unprecedented election victory in an unprecedented year. But Ms Harris, the California senator whose parents immigrated to America from Jamaica and India, will make a particular kind of history as the first woman, and the first person of colour, to be elected as vice-president of the United States.
The vice president-elect was born to an Indian mother, Shyamala Gopalan, and Jamaican father, Donald Harris, in 1964 and spent her early years in Berkeley, California.
She spoke of her childhood during the primary campaign, at one point putting her at odds with Mr Biden during a televised debate.
During a discussion about Mr Biden’s past opposition to school busing in the 1970s, she said: “There was a little girl in California who was a part of the second class to integrate her public schools, and she was bused to school every day. And that little girl was me.”
When Mr Biden picked her as his running mate, Sen. Harris tweeted a picture of herself as a toddler with her mother.
“My mother always use to say, ‘Don’t just sit around and complain about things. Do something,’” she wrote. “I dearly wish she were here with us this week.”
After her early childhood in California, she moved to Canada when her mother took a job at McGill University in Montreal. She went on to attend Howard University in Washington, DC before returning to San Francisco for law school, passing the bar in 1990.
While her career as a prosecutor, district attorney and state attorney general in California has drawn criticism from portions of the progressive left, her family background has thrilled many Black Americans and Indian-Americans – helping drive a massive fundraising haul for the ticket.
She has also received a warm reception in her mother’s homeland. In the days before the election, residents of her ancestral village of Thulasendrapuram, in Tamil Nadu in India, prayed for her success.
Ms Harris was the second black woman to be elected to the senate after Illinois’s Carol Moseley Braun, who served one term in the 1990s.
The Associated Press contributed to this report