A product of PAOK youth system in his homeland, Kyziridis went on to play for Iraklis and Volos before a two-year spell in Slovakia with Zlate Moravce.
He moved to Debrecen in 2022, helping them finish third in Hungary’s top flight and played in Conference League qualifying the following season.
This season, he finished third top scorer in the Slovakian top flight – four goals behind Tigran Barseghyan and David Strelec, both of champions Slovan Bratislava – as Zemplin narrowly missed out on the Championship group after their split.
Kyziridis becomes the second player signed by Hearts on a pre-contract agreement ahead of the new season, with Norwegian right-back Christian Borchgrevink poised to arrive from Valerenga.
The Greek is the first signing to be announced since Derek McInnes moved to Tynecastle from Kilmarnock as head coach on Monday.