Nnadi was born in
Ihiagwa, in the
Owerri West Local Government Area of
Imo State, Nigeria. He played football as a youngster with Campos FC in Owerri. In 2019, he began to train with Madenat Alamal Football Academy in
Dubai. After a successful trial, he joined
Botev Plovdiv in August 2021. He agreed a contract with the Bulgarian side until 2025. He made his league debut in the
Bulgarian First League on 3 April 2022, away at
Ludogorets. In his first season in Europe he made 19 league appearances for Botev Plovdiv, with 29 appearances coming in all competitions. On 19 January 2024, he joined Belgian
Belgian Pro League side
Zulte Waregem. On 2 February 2026, Nnadi signed with French club
Marseille. ==International career==