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.[2] He agreed a contract with the Bulgarian side until 2025.[3] He made his league debut in the Bulgarian First League on 3 April 2022, away at Ludogorets.[4] In his first season in Europe he made 19 league appearances for Botev Plovdiv, with 29 appearances coming in all competitions.[5]