Çollaku was born in Tirana. He competed at the 2004 Summer Olympics. He was placed thirty-first in the qualifying rounds of the competition, with a throw of 70.06 metres. At the 2008 Summer Olympics in Beijing, he successfully threw the hammer into the field on his third and final attempt, at 70.98 metres. Collaku, however, failed to advance into the hammer throw final, as he placed twenty-eighth overall in the qualifying rounds.