After moving to Atlanta, Williams joined the Young Democrats of Georgia.[3] She then served as vice president for public policy at Planned Parenthood Southeast.[4] In 2011, she was elected the first vice chair of the Democratic Party of Georgia.[5] She served as the party's interim chair in 2013, after Mike Berlon resigned.[2] In 2018, Williams became the State Director of the National Domestic Workers Alliance.[6]
Williams supported Barack Obama's presidential campaigns and served as a member of the Obama Victory Fund in 2012.[7] She was recognized as one of Obama's top bundlers during that campaign cycle, raising over $50,000 for the campaign.[8]
In January 2019, Williams was elected to once again lead the Georgia Democratic Party. She became the first Black woman, the third woman, and second African American to chair the party.[2] She was a delegate to the 2008, 2012 and 2016Democratic National Conventions. Senator Jon Ossoff reportedly pressed her to resign as Chair of the Georgia Democratic Party following the 2024 Georgia state elections.[11]
On July 20, 2020, after the death of John Lewis, Williams was selected to replace him on the November ballot for Georgia's 5th congressional district in the 2020 election.[14] The 5th is so heavily Democratic that Williams had been all but assured of a seat in Congress when she was selected to replace Lewis on the ballot.[15][16][17] Georgia Governor Brian Kemp called a September 2020 special election to fill the remainder of Lewis's 17th term. Williams opted to not run in the special election, choosing instead to focus on her role as party chair.[18] The special election was won by Atlanta city councilman Kwanza Hall, who served for a month before handing the seat to Williams. In the general election, she handily defeated RepublicanAngela Stanton-King by a 70-point margin.
Williams was one of two Democrats in December 2023 along with Bobby Scott to vote against the expulsion of now-former New York representative George Santos.[20]
Williams's husband, Leslie Small, was a former aide to John Lewis.[25] They met while campaigning for Democrats during the 2008 elections.[2] They have one son.[3] She is a former member of UFCW.[citation needed]