He becomes manager Craig Levein’s tenth capture of a hectic summer, with more new recruits still to come.
Haring, 25, invoked a clause in his contract allowing him to leave the Austrian second division club SV Ried after they failed to win promotion last season.
He arrived in Edinburgh, passed a medical and joined Hearts today to start the pre-season campaign. He will compete with Christophe Berra, John Souttar and the newly re-signed Aaron Hughes for places in central defence.
Levein wanted to add a centre-back to his squad after recruiting goalkeeper Zdenek Zlamal, left-back Ben Garuccio, midfielders Bobby Burns, Olly Lee, Ryan Edwards and Oliver Bozanic, winger Jake Mulraney, plus strikers Uche Ikpeazu and Steven MacLean.
Haring is known as a determined competitor who is useful in the air. He previously played in his homeland for Austria Lustenau, Rapid Vienna, Baumgarten, Schattendorf and Siegendorf.