During the race for the Democratic nomination, the 55-year-old described herself as a "progressive prosecutor" who backs law enforcement reforms.
Ms Harris eventually dropped out of the race in December 2019 with low polling numbers, and later endorsed Joe Biden.
She was a strong contender as a vice presidential running mate, and her selection makes her the first black woman and first Asian-American to be picked.
But who is Kamala Harris?
Born in Oakland, California in 1964, her father is Jamaican and an economist, and her mother was Indian and was a biologist who worked in breast cancer research. She died in 2009.
The name Kamala means lotus in Sanskrit and is another name for the Hindu goddess Lakshmi. Ms Harris accompanied her mother on trips to India throughout her younger years.
Her parents met at the University of California, Berkeley, where they were both involved in the civil rights movement.
They divorced when Kamala was seven and she was raised with her sister Maya by their mother in Berkeley.
During elementary school she was "bussed" from her predominantly black neighbourhood to her school as part of the attempts to diversify the racial make-up of schools.
That issue came up during the Democratic nomination race, when she challenged Joe Biden over his opposition to the desegregation policy.
Ms Harris attended Howard University, a historically black college in Washington DC where she studied political science and economics.
After attending law school back in California, she became a prosecutor and was hired as a deputy district attorney in Alameda County in 1990.
From there she became district attorney for San Francisco in 2003. During her first three years in the position, the conviction rate in the city jumped from 52% to 67%.
She also created a re-entry programme for low-level drug offenders and cracked down on student truancy.
In 2010, she won the race to become California attorney general - beating Republican Steve Cooley by just 0.8 percentage points and becoming the first woman and black person to hold the job.
She married lawyer Doug Emhoff in 2014, with her sister Maya officiating the ceremony.
In 2016, she won the US Senate race in California, beating fellow Democrat Loretta Sanchez who had 20 years' experience in Congress.
Here, she built a reputation around her work as a prosecutor, and gained national attention during her forensic questioning of Trump administration officials, including Jeff Sessions and Brett Kavanaugh.
Ms Harris launched her presidential campaign in 2019 with the slogan "Kamala Harris For The People", but eventually dropped out with dwindling polling numbers and a lack of funding.
She faced criticism over her record as attorney general, particularly towards her opposition to the death penalty and inaction over alleged police brutality.
Mr Biden then picked her as his running mate, describing her as a "fearless fighter for the little guy". Ms Harris was also close to his late son, Beau, who was also a state attorney general.