Mosaku was born in Zaria, Nigeria,[6] and subsequently emigrated to Manchester, England, when she was one year old. She attended Trinity Church of England High School and Xaverian Sixth Form College. She also sang for eleven years in the Manchester Girls Choir. Her parents were both professors in Nigeria. Her mother started a business and her father ended up returning to Nigeria.[4] Mosaku studied acting at the Royal Academy of Dramatic Art,[7] graduating in 2007, with a BA in Acting Degree (H Level).[7]
In 2008, she appeared in the first of the UNDEREXPOSED exhibitions at the National Portrait Gallery, designed to raise the profile of black role models and celebrates the talent that exists among the Black British community.[1] Her photo also appeared on Commercial Way, Peckham, London, as part of the exhibition. In 2009, she starred in the BBC Two series Moses Jones, for which she won Best Actress in a Miniseries at the Rome Fiction Festival.[8]
She featured on the front cover of Screen International magazine June–July 2009, as one of the UK Stars of Tomorrow, and in 2011 was featured in Nylon Magazine's 2011 Young Hollywood issue. In 2010, Wunmi Mosaku was named one of The Seven Fresh Faces of Toronto International Film Festival, for I Am Slave,[9] in which she starred. She plays Malia, a girl who has been kidnapped from her village in Sudan, and sold into slavery.[9] For her performance Mosaku won awards such as Best Actress at the Birmingham Black Film Festival, Best Onscreen performance at the Cultural Diversity Awards and Best Female performance at the Screen Nation Awards.[9]
When asked to list her personal heroes, Mosaku included her grandmother Anike Adisa, whom she described as having "taught me so many lessons"; actor Albert Finney, who was her inspiration for attending the RADA; her colleague and former instructor at RADA, William Gaskill; Paul Newman, whom she admired, not just for his acting, but also for his philanthropic efforts with Newman's Own; and Oprah Winfrey, who Mosaku considers "a superwoman".[12]