"Unbelievable, love ur [sic] dedication and hard work," wrote one social media user.
"Looking good," said another person.
"You've always been in shape, but this is next-level," one added.
Even his celebrity mates got in on the praise.
E! presenter Mario Lopez wrote: "BEAST!"
American rapper Fat Joe described his physique as "the best shape of your life".
Mark has previously opened up about the gruelling reality of maintaining such a high level of fitness — especially as he also owns a delicious burger chain in the US.
He first sculpted his signature six-pack back in the early '90s as rapper Marky Mark in New Kids On The Block and a part-time Calvin Klein model.
But during his physical preparation for $6 Billion Man the dad gave fans a glimpse into his gruelling fitness regimen, and boy – it's completely hectic.
Revealing his "typical daily routine" in an Instagram Stories once, the dad said he wakes up at 2.30am every day.
By 5am when the rest of the world is mostly still asleep, he's already eaten breakfast and completed his first workout.
At 7.30am he heads for a spot of golf and will complete a cyro chamber recovery session on his way home before having his second snack of the day.
At 11am, he pauses to enjoy "family time" before completing tasks like work meetings and picking the kids up from school — and of course, squeezing in lunch and more snacks.
Then at 4pm he trains again, before having dinner with the family and heading to bed at 7.30pm. Woah.
It's not just the physical side that is intense, his diet is too.
Back in 2017 he gave an insight into his meal plans, revealing he started his day in the most bizarre way — roasting a chook.
"I roast it myself, stick it in the rotisserie — tie the legs, tie the wings, tuck it in, season it," he said on Live with Kelly.
"I start at, like, 2am," Wahlberg explained.
"Egg whites and Ezekiel bread with some almond butter. Then I have some Greek yoghurt and a shake. And turkey burgers with sweet potato. Then I have a chicken."
Mark said in the same interview that his four children aren't massive fans of his daily roast chicken habit.
"The kids are eating pancakes ... and the whole house smells like chicken. They are like, 'Dad, you are disgusting'."
Earlier in 2019, he invested Australian fitness franchise F45, officially bringing it to the US.
The buff "fitness enthusiast" reached out to CEO Rob Deutsch to ask if he could get involved when he "fell in love with the concept" after taking a class in November 2018.
"It was magic to see people, who might have been sluggish or tired, walk out after a class with huge smiles on their faces," Wahlberg said.
"I thought, 'This is the business I want to be involved with,' and 'This is the work out that I want to do'. I thought, 'How do I get involved with this?'"
The star now regularly trains at a franchise in LA's Sherman Oaks, regularly sharing snaps on his Instagram from his sweaty sessions.
