The 29-year-old Kiwi has put pen to paper on a two-year deal at the Dons after becoming a free agent at the end of the transfer window.
Fallon has spent all of his domestic career in England becomes the third former Plymouth Argyle player to arrive at Pittodrie during summer, along with Chris Clark and Kari Arnason.
The forward has played 11 times for his country, scoring three goals, the most famous of which sent New Zealand into their first appearance in the World Cup finals in 28 years in the play-off against Bahrain.
The striker goes straight into the squad for Saturday's home game against Kilmarnock in the SPL, subject to international clearance.