Jeremy popped the question to his girlfriend, Chelsey Rebelow, in February while they were vacationing in St Barts.
The engagement party appears to have been held at a private art show, simultaneous to an event called the "Nyotaimori Celebrating Life Love And Art", reported People magazine.
Bieber, 22, spent time at the party petting the tiger - a moment he later Instagrammed - and hanging out in the Batmobile and the superheroes, as well as with his father.