The duo are part of the club's 31-man squad for the group stages of the competition.
Obi has been part of Inter's Primavera squad, while Obiora joined the treble winners in January after spending time in Spain.
He was a member of the Nigeria squad to last year's FIFA Under-20 World Cup in Egypt.
Inter Milan's 2010-11 Champions League Squad:
Goalkeepers: Julio Cesar, Luca Castellazzi, Paolo Orlandoni, Alberto Gallinetta
Defenders: Ivan Cordoba, Javier Zanetti, Lucio, Maicon, Marco Materazzi, Walter Samuel, Cristian Chivu, Davide Santon, Felice Natalino, Cristiano Biraghi, Andrea Romano, Lorenzo Crisetig
Midfielders: Thiago Motta, Wesley Sneijder, Sulley Muntari, MacDonald Mariga, Esteban Cambiasso, Dejan Stankovic, Amantino Mancini, Joel Obi, Coutinho, Obiora Nwankwo
Attackers: Samuel Eto'o, Diego Milito, Goran Pandev, Jonathan Biabiany, Simone Dell'Agnello