Simon Webster, the club's head of Commercial, said: "This is an outstanding agreement for the club and a true first in football.
"The link up with Bet24 provides a lucrative and mutually beneficial partnership, but it is the additional support in key territories from the parent company MTG that sets this deal apart and underlines the growing support for the re-emergence of Leeds United. It is terrific that we continue to grow a family of partners who play an important role in helping the club back to the top."
Chairman Ken Bates added: "It is a substantial deal and it is one that quite a few Premier League clubs would be more than happy with. We have worked closely together with Bet24 before, but this takes things onto a new level."
MTG'S Viasat TV channels reach 60 million people across Europe and every United match next season, irrespective of which division, will be broadcast live on the continent.
MTG is the largest free-to-air and pay-TV operator in the Nordic and Baltic regions and covers all of Scandinavia, the Baltic states, Russia, Poland, Hungary, Bulgaria and Germany.
Bates also revealed that United are hoping to unveil an official broadband partner in the near future, as the club look to further increase their profile.