EXCLUSIVE: Billionaire businessman Justin Hemmes, 48, and his model girlfriend Madeline Holtznagel, 25, enjoy a playdate at a park with his two young daughters in Byron Bay

Justin Hemmes and his model girlfriend Madeline Holtznagel treated his two young daughters to a playdate at a park in Byron Bay on Monday.

The 48-year-old billionaire businessman and his much younger girlfriend supervised the two little girls as they played nearby on a tube slippery dip.

Madeline, 25, stuck close to Justin during the outing, with the pub baron cycling with daughters Alexa and Saachi on the front of his bike.

Family outing: Justin Hemmes and his model girlfriend Madeline Holtznagel treated his two young daughters to a playdate at a park in Byron Bay on Monday

Justin shares Alexa, four, and Saachi, three, with his former partner, Kate Fowler.

The renowned businessman was dressed casually in a pair of white shorts, which he paired with an oatmeal-coloured T-shirt.

He also wore white sneakers, and his long blond hair was tied back in a half-up, half-down style.

Dad duty: The 48-year-old billionaire businessman and his much younger girlfriend supervised the two little girls as they played nearby on a tube slippery dip

Good jeans: Madeline opted for a dark blue denim miniskirt, which she paired with a matching halterneck crop top

Meanwhile, Madeline opted for a dark blue denim miniskirt, which she paired with a matching halterneck crop top.

She also wore white sneakers, and accessorised with a pair of dark sunglasses and a pale pink handbag.  

They appear to be riding out Sydney's current COVID lockdown in Byron Bay, which hasn't been as adversely affected. 

Keeping a low profile: They appear to be riding out Sydney's current COVID lockdown in Byron Bay, which hasn't been as adversely affected

Ride on: Madeline, 25, stuck close to Justin during the outing, with the pub baron cycling with daughters Alexa and Saachi on the front of his bike

While it's not known exactly how long Justin and Madeline have been dating, she hinted their relationship has carried on longer than many people expect.  

Speaking to The Sydney Morning Herald in October, Madeline said they'd actually met two years before reports emerged of their relationship early last year. 

'We have known each other for two years and met when I was modelling in Singapore,' she said at the time.

Secret romance: While it's not known exactly how long Justin and Madeline have been dating, she hinted their relationship has carried on longer than many people expect

It was also reported that Madeline was living in a penthouse apartment owned by Justin in the Sydney beachside suburb of Coogee. 

She added that while the majority of her family was yet to meet her beau, her older sister, Simone, 28 - who appeared as a finalist in the 2011 season of Australia's Next Top Model - was a fan.

'My parents and my sister Anna haven't met him yet but Simone has been introduced to him and really liked him,' she added.  

Still going strong: Speaking to The Sydney Morning Herald in October, Madeline said they'd actually met two years before reports emerged of their relationship early last year