Dimas born in Himara (or Chimara), Albania to parents of Greek origin. He emigrated to Greece in 1991 and subsequently changed his name to Pyrros Dimas. He first competed for Greece in the 1992 Summer Olympics, winning the gold medal in the 82.5 kg class. His birthplace gave rise to the his nickname "The Lion of Chimara".
With the 1993 and 1995 World titles under his belt, Dimas was heavily favoured for the 83 kg class at the 1996 Summer Olympics. He won the event with two new World Records.
At the Sydney Olympics, he won yet another gold medal, this time in the 85 kg class. This made him one of just three weightlifters to have won three Olympic gold medals, the others being Naim Suleymanoglu (Turkey) and Akakios Kakiachvilis (Greece). Incidentally, both of these weightlifters were also born in another country; Suleymanoglu in Bulgaria, and Kakiachvilis in Georgia.