Cricketer David Warner, his wife Candice, model twins Jordan and Zac Stenmark, athlete Amy Pejkovic, and glamour couple Elle Ferguson and Joel Patfull all attended the training session in Woolloomooloo on Tuesday morning.
The celebrities completed an intense workout led by the 47-year-old actor, who invested in the Australian fitness franchise last year.
Mark bought a minority stake in the gym chain with his company, the Mark Wahlberg Investment Group, and FOD Capital.
F45 refers to the 45-minute high-intensity functional workouts the gym is famous for.
The company has 1,500 studios across 40 countries and is the fastest growing fitness franchise in the world.
Meanwhile, Mark showed off his ripped body in a tight black T-shirt and grey trackpants at the training session.
The Daddy's Home star completed his ensemble with a black hat and white sneakers.
Mark is reportedly in Australia to film an advert for online betting agency Ladbrokes.
The actor was spotted arriving in Sydney with his entourage via private jet earlier this month.
Footage showed the Patriots Day star emerging from his jet flanked by security guards holding umbrellas.
The A-lister shares four children with his wife, Rhea, daughters Ella-Rae, 15, and Grace, nine, and sons Michael, 12, and Brendan, 10.