Karalis was born on October 20, 1999, the son of Haris Karalis - a Greek decathlon athlete - and an Ugandan long jump female athlete. He is an athlete of Kifisia Athletic Club and trains under Vasilis Megaloeconomou.
On March 5 of the same year, he improved his world junior record with a jump of 5.54m in Jablonec, Czechia.
On May 20 still that same year, Karalis jumped 5.55m, in Ostrava, improving his record yet again.
His personal best jumps are currently (January 2019): 5.63m. outdoor and 5.80m. indoor.