Brought to the first team squad by José Mourinho, he made his professional debut for Roma on 16 January 2022, replacing Maitland-Niles in the last moments of a 1–0 home Serie A win against Cagliari.[2][8] By doing so, he became the first player born in 2004 to play for the club,[9] and the third-youngest foreigner, behind his compatriot Lampros Choutos.[6]
On 6 September 2024, Keramitsis signed a three-year deal with Polish Ekstraklasa club Pogoń Szczecin.[12] He made his debut in Pogoń's second team on 15 September 2023, in a 1–1 draw against Unia Swarzędz. He made his Ekstraklasa debut on 20 October, in a 1–0 away loss over Raków Częstochowa.[13] In the 65th minute of that match, he was given with a straight red card for fouling Adriano Amorim.[14][15] One month later—on 24 November 2024, Keramitsis was shown a second yellow card during a 0–0 draw played against Elana Toruń in Pogoń's reserve team.[13]
A right-footed centre-back who also makes good use of his left foot—allowing him to build the game from the back—he is described as a physical player, good at marking his opponent and with a fine sense of timing, able to play both in a 3 or 4-men defense.[2][5][7][3]
In his early career, his origins and his debut at Roma soon earned him comparisons with the international defender Kostas Manolas.[3][7][8]