The 33-year-old Welshman matched the record of the legendary Arnold Schwarzenegger – who is one of the biggest icons in the bodybuilding industry – and also won the crown six times in a row.
We caught up with Flex after the show to find out where his fitness journey began and what kind of work went into sculpting his mind-boggling muscular physique.
Speaking exclusively to Daily Star Online, Flex said: “I have been training since I was 14-years-old, so 18 years of training in different sports have helped develop my muscles and create a solid foundation."
He continued: “In this sport your physique actually gets better with age. This is due to muscle maturity.
"So we have men competing who are in their 40s beating people in their 30s.
“With that said, the sport of bodybuilding is very unique and one that you continue to perfect your craft.
“Age helps you and doesn’t hinder your progress, contrary to other well known sports.”
To maintain his bulging biceps and shredded six-pack, the dad-of-one trains in the gym for 60 to 90 minutes per day.
In the run-up to a big competition like Mr Olympia, Flex revealed his diet and training routine becomes more regimented.
“I try to train at the same time each day for consistency in my day,” he explained.
On top of that he chows down on between six and seven meals per day.
But it doesn’t mean that he never indulges in junk food or a night of boozing.
Flex said: “My life is about balance.
“I have a wife and beautiful soon to be 2-year-old and I love to enjoy life with them both.
“Even during my prep I get cheat meals to help maintain a certain desired weight.
“During my ‘off season’ I eat very clean, and to be honest usually eat a lot less meals per day, since I honestly can say I do not like to eat (ironic I know).
“I will also indulge in a drink here and there in social setting as well.”