Mojekwu was born in Brixton, South London, in 1989 to Nigerian parents. She is the eldest of four children. In 2006, her family moved to Kent.
Mojekwu began acting at school with a small role in The Wizard of Oz. She joined Identity Drama School in Kent in 2006 and won the school's Actress of the Year award in her first year. Mojekwu went on to play Paris in Bola Agbaje's award-winning play Gone Too Far!. In 2008, she starred as Ronnie in Channel 4's Fallout and in 2009 she got the part of Mercy Olubunmi in the Internet teen drama EastEnders: E20, a spin-off from the long-running BBC One soap opera EastEnders, which was broadcast in January 2010. Following this, she was contracted for six months to appear in EastEnders as Mercy Olubunmi. She left EastEnders on-screen on 12 July 2011.