Judges applauded Adichie's sophisticated approach to gender, race and global inequality.
Speaking on the award, Adichie described the award as an honour. "I admired Harold Pinter's talent, his courage, his lucid dedication to telling his truth."
Adichie will be receiving the award at a ceremony at the British Library in October, where she will also deliver an address.
A limited edition anthology of 10 Pinter Prize lectures will be printed to celebrate the prize's 10th anniversary.