Asante was born in London in 1969, to Ghanaian parents; her father was an accountant, and her mother ran a deli. She was a childhood friend of model Naomi Campbell whom she met when they were seven years old.
Asante attended the Barbara Speake stage school in Acton, London, where she trained in dance and drama. She began her film and television career as a child Actress, appearing as a regular in the British school drama Grange Hill. She appeared in the "Just Say No" campaign of the 1980s and was one of nine Grange Hill children to take it to the Reagan White House. She gained credits in other British television series, including Desmond's (Channel 4) and Birds of a Feather (BBC1), and was a Children's Channel presenter for a year.
In her late teens, Asante left acting and worked in screenwriting with a development deal from Chrysalis. She founded a production company, Tantrum Films, and wrote and produced two series of the BBC2 drama Brothers and Sisters (1998– ).
In November 2004, the London Film Festival awarded Asante the inaugural Alfred Dunhill UK Film Talent Award. In February 2005 Asante was awarded The Times's Breakthrough Artist of the Year and nominated for Best Newcomer at both the Evening Standard and London Film Critics award ceremonies.
It was distributed through Fox Searchlight Pictures. On 19 September 2013, the Daily Mail reported that Asante was denied writing credit on the film, due to arbitration about contested credit by the Writers Guild of America.
Asante is a past elected member of BAFTA Council and a past BAFTA Film committee member. In 2014 she was made an Honorary Associate of the London Film School where she earlier served as a Governor (2006–2007).
In June 2016, the BFI announced that A United Kingdom would open the 60th London Film Festival.
Asante was appointed Member of the Order of the British Empire (MBE) in the 2017 Birthday Honours for services to film.
