The move has been on the cards since the Bafana Bafana striker began training with the team at the end of last month, but will still come as some disappointment to Buccaneers supporters.
Rantie was instrumental in the club’s fine run of form in the final few weeks of last season, which saw them clinch the Premiership title.
The fan-favourite later made his national team debut, scoring on his second appearance for Bafana against Gabon in a friendly in June.
Pirates did make a R2-million offer for the player at the end of the last campaign but his club, Swedish lower league side Hässleholm, rejected it.
Malmo will have the option to sign him outright at the end of his loan for an undisclosed figure.
"Malmo are a good team with a proud history. I have seen what the club has achieved and it will be great for me to get the chance to practice and play in such a team," Rantie told Skanskan.se. "This I have been hoping for since I came here. This is a higher level for me than I have previously experienced. I am ready to fight for my place in the side."
Rantie will have to wait for his debut, however, as he has yet to receive his work permit, though this is seen as a formality.