Halys, ranked 64th in the world, has never beaten a top-10 opponent but gave Djokovic a big scare before the former world number one prevailed in two tiebreakers.
Djokovic, who has now won 31 consecutive singles matches in Australia, is preparing for the January 16-29 Australian Open, where he is seeking a record-extending 10th crown.
The Serb was unable to defend his title last year after he was deported on the eve of the tournament for not being vaccinated against COVID-19.
"It was a great performance from my opponent today. I want to congratulate him for great quality and a great fight. Tough luck but he played like a top 10 player today, no doubt," Djokovic, now ranked fifth in the world, said.
"As far as my game goes, I feel good on the court. I didn't have such a great start, I lost my serve early. He was serving really well, fast, big serves, hitting his spots in the box very well.
"Just difficult to play in this kind of court that is really fast. It kind of favours the server. If you're serving well, it's tough to break the serve of a big server like him, so two tiebreaks were probably the most realistic score."
The Serbian will next play Denis Shapovalov, who he has beaten in all seven of their meetings.
"Denis is one of the most complete players out there, he's got a very dynamic style of tennis, a big serve, comes to the net and (he is) comfortable playing from the back of the court," Djokovic added.
"He's a very great athlete, moves fantastically. We haven't played for a while so I'm looking forward to that. Every match now gets tougher, I'm going to be ready for that."
