The S8 model is the first from the company since its disastrous flammable Note 7 model which saw the company recall millions of devices, wiping billions off its market cap.
Spark chief executive of home, mobile and business Jason Paris said the hype around the latest device had helped drive pre-sales.
"It is easily the phone that's pre-sold the most of any devices we've ever had and it's three times any other Samsung device we've sold," Paris said.
"There's a real trend towards premium devices now so anytime a new premium device comes out from Apple or Samsung it's bigger than the last," he said.
"The quality of the devices are extraordinary now in terms of what you can do with them."
Paris said he could not give specifics on how many devices had been sold, but said the company had guaranteed pre-sale customers would be the first to receive the devices before it went on sale to the public today.
It had also allowed pre-orders through online, in store and its call centre, providing a greater opportunity for customers to pre-purchase the device.
"There has also been a lot of hype around this device internationally - people are genuinely excited about what the device could do for them," Paris said.
Samsung has also launched a number of additional products to pair with the Galaxy S8's including new virtual reality gear and the Samsung DeX - allowing the phone to be used like a desktop computer.
The Samsung Galaxy S8 and S8+ will feature larger 5.8 and 6.2-inch screens with a water-resistant body, improved selfie camera, and a smart assistant named Bixby that takes voice commands, although this isn't fully functional in the phones yet.
