The powerful Belarusian, who came from a set down to beat Elena Rybakina in the final 12 months ago, was in a different class on her way to a 6-0, 6-1 victory in just 53 minutes on Rod Laver Arena.
Seidel, playing her debut Grand Slam, won only 10 points in a 22-minute first set demolition, making multiple unforced errors as Sabalenka imposed herself.
It did not get much better in the second set as the world number two kept up the hard-hitting barrage, with her serve unstoppable.
"Super happy to be back in Melbourne -- I have incredible memories from here," said Sabalenka.
"Hopefully I can stay here till the very last day.
"I still need to work for my dreams. It's been so amazing I have been able to achieve so many goals in my tennis and there are more to come."
Sabalenka enjoyed a breakthrough 2023. As well as winning the Australian Open she also made the semi-finals in Paris and at Wimbledon before losing to Coco Gauff in the final of the US Open.
In doing so, she became the first player since Serena Williams in 2016 to reach at least the semi-finals at all four Slams in a single season.
She carried the momentum into 2024, reaching the final at the recent Brisbane International, losing to Rybakina, before teaching Seidel a lesson in Melbourne.
