Heart head coach John Aloisi was delighted to welcome the talented central midfielder Engelaar to the club.
"I am confident that Orlando will be one of the most accomplished midfielders that has come to play football in Australia," said Aloisi.
"The Club has worked hard for a number of seasons to attract a player who can dominate and control matches from midfield and we believe that we have found that player.
"You don't pull the strings in the midfield for the Dutch national team unless you have some special qualities. We can't wait for the season to get started and, with this signing, believe that we have given football fans something to get really excited about."