The UFC made the announcement Friday.
Arlovski (27-15) is back on a two-fight win streak after enduring a five-fight skid. The 39-year-old is coming off a decision win against Stefan Struve at UFC 222 earlier this month.
Tuivasa (7-0) is a 25-year-old prospect out of Sydney, Australia. He is 2-0 in the UFC with two first-round finishes.
All of Tuivasa's professional wins, in fact, have come via first-round knockout. His most recent win came against Cyril Asker at UFC 221 in Perth, Australia.