The 26-year-old Argentinian has been sidelined since last February with a wrist injury but he showed little sign of rustiness as he began the defence of his Sydney title with a 6-3 7-6 (7/4) victory.
He said after his first-round victory on www.atpworldtour.com: “It was a great moment for me.
“I think I played well in my first match after 10 months. I served well. My forehand is still working out. So that’s a good signal for the future.
“I need to work very hard to my backhands and my movements, but I think now is time to think about my comeback and enjoy this moment a lot.”
The 2009 US Open champion, who has dropped down to 338th in the world, will face top seed Fabio Fognini in the second round.
Del Potro added: “I think the wrist is okay. I will be ready to play tomorrow for sure. I will do treatment; it takes me like an hour every day.”
Home hope Bernard Tomic, who was beaten by Del Potro in last year’s final having won the title in 2013, also safely progressed to the second round as he swept aside Dutch qualifier Igor Sijsling 6-1 6-2 in just 43 minutes.
Seventh seed Jeremy Chardy is also through, the Frenchman seeing off Sam Querrey 6-4 6-4, but it was not such a good day for number eight Martin Klizan, who was dumped out in under an hour as Viktor Troicki recorded a 6-4 6-4 win.