He is currently the head coach of Lokomotiv Novosibirsk and the Bulgaria men's national volleyball team.

Konstantinov finished a sports school and started his career with Levski Sofia in 1986, where he remained until 1995; he spent some of the following season with Slavia Sofia and then moved to Italy to play for the Gioia del Colle team.

From 1999 until 2004 he played in Greece for Orestiada, PAOK Thessaloniki V.C., Iraklis V.C., Olympiacos S.C. and Panathinaikos VC.

[2] With Iraklis Thessaloniki he won the silver medal at the 2008-09 Indesit Champions League and also was individually awarded "Best Receiver".

[2] In 2008, he was voted Bulgaria's Man of the Year in an online poll organized by Darik Radio.