Mayweather had attempted to spread rumours about McGregor struggling to make the weight limit, but he's never missed weight in his career and didn't this time.
"I'm a professional, I make weight. It's sacrifice, it's dedication, it's focus, but I make it," the Irishman said.
"Look at me, I'm in peak physical condition. I've put in the work as everyone can tell. I'm ready.
"(I'll be) a lot bigger than him (by the time of the fight). I'd say close to 170, yes."
McGregor also brushed off Mayweather's new favourite line about his opponent being able to "not just give it, but take it".
"I'll stomp my foot right in the centre of that ring. I won't go nowhere other than the centre of that ring. So let's see who can take it," McGregor said. "He's over there twiddling his thumbs, twitching away. I see a man afraid."
McGregor walked out topless draped in an Irish flag, with Irish coloured headphones around his neck, flip-up sunglasses, green track pants and open toe slippers.
McGregor had a significantly pro-Irish crowd roaring before Mayweather emerged in a white hat and T-shirt, grey track pants, white sneakers and - it was revealed after he stripped down - green "Paddypower" underpants.
Mayweather skipped across stage taunting McGregor and wasn't phased by the reading on the scales.
"I've been here before. I know what it takes when it's a fight of this magnitude. Weight doesn't win fights. Fighting wins fights," he said.
"It won't go the distance. Mark my words. I'm not really worried about the scale or (that it's his) last time. This will be Conor McGregor's last fight also."
LEGEND LANDS A SHOT
Boxing legend Oscar De La Hoya has sent another barb in the direction of Floyd Mayweather and Conor McGregor, just as the two prepare to hit the scales ahead of their superfight.
De La Hoya, who has long been critical of the Mayweather-McGregor showdown, took to social media to fire a heated message at the pair.
"F*** you, Mayweather-McGregor. BOTH OF YOU ARE DISRESPECTING THE SPORT OF BOXING #CANELOGGG Sep. 16th," De La Hoya tweeted.
De La Hoya's Golden Boy company will promote the long awaited blockbuster between Saul "Canelo" Alvarez and Gennady Golovkin on September 17 (AEST).
That showdown will rival the Mayweather-McGregor fight for fan interest, but many believe the box office appeal of Canelo-Golovkin will be hurt, being so close to the combat sports mega event - which is the main reason for De La Hoya's angst.
Also, rumours have swirled in recent days that Conor McGregor was battling to make weight for his highly anticipated super fight with Floyd "Money" Mayweather.
It has added to the anticipating surrounding Saturday's (AEST) weigh-in, but Team McGregor has ensured there will be no shocks when the UFC star hits the scales.
McGregor's coach John Kavanagh tweeted prior to his fighter's arrival at the weigh-in that the UFC lightweight champion would have no such issues reaching the super welterweight mark.
A hoard of Irish fans started gathering for the moment the fighters will step on the scale six hours before it began. Dozens of security guards are on hand to keep them in check.
Mayweather taunted the Irishman earlier this week by warning him he could lose millions if he doesn't drop 10 pounds before hitting the scales.
The 40-year-old expressed concerns that McGregor is looking like coming into fight night over the weight limit of 154 pounds.
The American, whose boxing record sits at an untouchable 49-0, is so confident of beating McGregor he decided to wolf down some Burger King just days before the fight.
Catch all the action from 10am in the stream below:
