FIBA Europe
Vezenkov was a member of the Bulgarian junior national teams. With Bulgaria's junior national teams, he played at the following tournaments: the 2010 FIBA Europe Under-16 Championship, the 2011 FIBA Europe Under-16 Championship, the 2012 FIBA Europe Under-18 Championship, the 2012 FIBA Europe Under-20 Division B Championship, and the 2013 FIBA Europe Under-18 Championship. He led the 2011 FIBA Europe Under-16 Championship in scoring, with an average of 27.1 points per game.