It is their second foreign signing of the season, having roped in forward Yu Kuboki from Australian club Sydney Olympic FC earlier.
Njoku is a 22-year old pacey, versatile midfielder who can slot in at different positions at the centre of the park. He has previously plied his trade for FC Inter, a Finnish first-tier side.
He managed to score eight goals and three assists in his 58 appearances in the Finnish league while operating as an attacking midfielder and as a right winger.
After the departure of Bhutanese sensation Chencho Gyletshen, the I-League champions will now look up to the partnership of Kuboki and Njoku for goals upfront.
Minerva are rebuilding their squad from scratch as their star performers of previous season have left for greener pastures. While Kamalpreet Singh and Rakshit Dagar have joined East Bengal, left winger Abhishek Ambekar, striker Moinuddin Khan and defender Sukhdev Singh have joined Mohun Bagan.
Former National Football League (NFL) winning coach Sukhwinder Singh has been roped as a tecnical director. The veteran tactician will work jointly with the current technical director Surinder Singh and head coach Sachin Badadhe.