After Destiny's Child's disbandment in 2006, Williams released her first pop album, Unexpected (2008),[7] which spawned the singles "We Break the Dawn" and the US Dance number-one "The Greatest".

[11] Williams was a featured judge on MTV's Top Pop Group, a contestant on season 8 of Strictly Come Dancing in the United Kingdom, and has also appeared on the American, British, and Australian versions of The Masked Singer.

[14] Williams made her musical debut at the age of seven, performing a rendition of the hymn "Blessed Assurance" at the St. Paul Church of God in Christ.

[16] Shortly after graduating, she pursued a degree in criminal justice at Illinois State University, doubtful of her ability to make a career as a professional singer.

[17] In late 1999, 20-year-old Williams met Destiny's Child band members Beyoncé Knowles and Kelly Rowland in the lobby of an Atlanta hotel.

[19] After the much-publicized turmoil, Williams, alongside Farrah Franklin, officially joined the group in early 2000, replacing LeToya Luckett and LaTavia Roberson without notice.

[20] After settling on this final lineup, the trio released "Independent Women Part I", which appeared on the soundtrack to the 2000 film Charlie's Angels.

Sponsored by Burger King, the 19-date BK Got Music Summer Soul Tour also featured Luther Vandross, Angie Stone and Gerald Levert.

[43] Released in January 2004 in the United States, Do You Know reached number 120 on the Billboard 200 chart, despite a warm reception from critics who lent praise to Williams' songwriting ability.

[53] Beginning in April 2007, Williams joined Oprah Winfrey's Chicago-based cast of the hit Broadway musical The Color Purple for its national tour, starting with an extended run at the Cadillac Palace Theatre.

Williams described the opportunity as "a dream come true",[54] playing the part of blues singer Shug Avery, which earned her positive reception.

In June 2008, Williams released lead single "We Break the Dawn" to universal acclaim from critics who hailed it as "a terrific fusion of European disco and American R&B".

[65] In July 2009, Williams began a limited six-week engagement at the Cambridge Theatre in Chicago, making her the first African-American to be cast in the West End production of the musical.

[68] In February 2010, Williams made a return to Broadway by commencing a seven-week limited engagement in Chicago at the Ambassador Theatre, replacing Ashlee Simpson.

[75] They remained in the competition for seven weeks with variable results; on October 23, Ian Waite stood in as her professional partner when Brendan was unable to do so.

[76] In December 2010, Williams joined DJ Martin Jay to become a co-host on Choice FM's Breakfast Show in London for the month, replacing Lucy Ambache who was on maternity leave.

[77][78] On December 15, Williams released the song "Stay for a Minute", a leftover from Unexpected for free digital download via Twitter to celebrate gaining over 100,000 followers.

[93] In December, Ultra Naté released a joint collaboration with Williams titled "Waiting on You" which rose to number eleven on the Billboard Hot Dance Club Songs chart.

[106] It was announced that Williams would star as a mentor in an Oxygen reality television competition titled Fix My Choir, alongside fellow contemporary gospel recording artists Deitrick Haddon and Tye Tribbett.

[125] Williams also returned to Broadway as Erzulie in the Tony Award-winning revival of Once On This Island on November 30, 2018, leaving in December on doctor's orders.

[128][129] On December 21, it was announced by Deadline Hollywood that Williams would guest star as Diana Ross in an episode of the BET period drama series American Soul, which aired in February 2019.

In December 2019, she came back to the stage starring as the Evil Queen for the 10th anniversary of A Snow White Christmas at the Pasadena Civic Auditorium, alongside Neil Patrick Harris and Jared Gertner.

[148] In March 2024, Williams was cast in the musical adaptation of Death Becomes Her, playing Viola Van Horn (Lisle von Rhuman in the film version), at the Cadillac Palace Theatre in Chicago from April 30 to June 2.

[151][152][153] William Ruhlmann of AllMusic commented that she has a "warm, kittenish voice" with the ability to "transform" from "kitten to tiger", belting "with absolute conviction".

[44] Sal Cinquemani of Slant Magazine compared her to other singers, writing "Williams's warm vocal recalls both the playful wisps of her R&B contemporaries (Jill Scott, Erykah Badu) and the breathy timbre of Diana Ross".

[155] Emily Sogn of PopMatters wrote "Williams singing style is pleasingly slow paced...that owes a lot to her pop contemporaries like Ashanti and Janet Jackson.

[160] In September 2018, the couple revealed plans to film a television series, showcasing their relationship as they navigate the road from engagement to marriage.

[164] Williams suffered a nervous breakdown just after opening day for a Broadway production of Once on This Island and was advised to leave the show by her doctor.

[164] In November 2020, Williams announced plans to release a memoir "revealing her entire truth including a deeper dive into where her anxiety and depression came from."

"[173] In 2014, Williams partnered with Hyundai's non-profit organization, Hope on Wheels, "committed to finding a cure for childhood cancer"; which has raised over $74,000,000 for the cause since its inception in 1998.