Horie, who played for Japan at last year's World Cup, is poised to join Panasonic Wild Knights team-mate Fumiaki Tanaka in the southern hemisphere's premier competition.
Both Horie and scrum-half Tanaka, who has signed for the Dunedin-based Highlanders, played for Otago in New Zealand's ITM Cup earlier this year.
"I am very honoured to become a member of the Melbourne Rebels," Horie said in a statement released by the Wild Knights.
"I hope to contribute as much as I possibly can to the team's victory and to demonstrate what Japanese players are capable of in Super Rugby.
"I owe a lot of people, not just at Panasonic, for this opportunity and I will do my best to repay them for all their support."
Rebels head coach Damien Hill said Horie would quickly make his mark at the Rebels.
"The work ethic of all Japanese players is of the highest order," said Hill, who had a three-year spell coaching in Japan.
"To have him as part of this club will have an immediate impact."
Hill added: "He comes with a point to prove, as do most of our players we bring from afar. That drive will be infectious and will bring the best out of all the hookers at the club."
Horie, who has won 19 caps for Japan, is set to join up with his new Rebels team mates early next month.