His family moved to Tirana when he was 14, where he graduated at Qemal Stafa High School.

In 1947, he participates in the competition at the National Theatre of Albania and wins.

He has created unforgettable characters such as Vuksani in "The second face" (Albanian: Fytyra e dytë), Horatio in Hamlet, Otello in Otello, Miller in Intrigue and Love from Schiller, Dhaskal Todri in "Letter's way" (Albanian: Udha e shkronjave), Ismail Qemali in "Second November" (Albanian: Nëntori i Dytë), etc.

His death in 1985 created many controversies in Albania, as it was talked as a suicide, these were just never proved gossips, and the media never reported his end of life as such.

In 2010, Prosi was awarded the Honor of the Nation title (Albanian: Nder i Kombit) by the President of the Republic of Albania.