Κostas Κonstantinou studied bass and electric bass on scholarship at Berklee College of Music in Boston. He graduated with highest honors and a prize as 'prominent double bass performer'. During his studies he participated in many concerts at Berklee and in the area of Massachusetts.

Upon his return to Greece he worked with major jazz musicians of the Greek scene and musicians from abroad (Lou Donaldson, Peter Berstein, Montenia, Mario Reyes, Jarmo Savolainen, Andy Sheppard, Ralph Peterson, Antonio Rivas, Alfredo Rodriguez, Craig Bailey, Vincent Hector, John Vidakovich, Gene Calderazzo, Alvester Garnett, etc.). He appeared in Greek and international festivals (Athens, Thessaloniki, Santorini, Olympus, Cyprus, Bucharest, Hanover, Beijing, Bursa, Valencia, etc.), and he collaborated with the Third Programme of the Greek Radio. Among other events, he performed at the Presidential Palace (Festival of Democracy, Youth Parliament, etc.). He has also been a key member of the radio and television program Jazz Club of Three. He has participated in recordings such as: Secret Path by D. Vassilakis (Candid), Liberte by Kad Achoury (Etera), Tribute to Hank Mobley by S. Vougas (Legend), Blink by G. Polyhronakos (Legend), The Story Teller by G. Kontrafouris. He has also recorded the album Concentric Cycles with his own compositions, collaborating with pianist Tsabropoulos (Nabel Records). Since 1997 he has been teaching at the Philippos Nakas Conservatory, having been appointed artistic director of the Modern Music Department in 2011.