The Wimbledon champion broke the 22-year-old Haddad Maia twice in the opening set and converted her first set point when the Brazilian sent a forehand wide for her 29th unforced error in the set.
Kerber, a triple Grand Slam champion who won in Melbourne in 2016, faced just one breakpoint in the match in the second set and converted her first opportunity in the eighth game to go 5-3 up and serve for the set.
"I think it was a good match from my side. I was trying to play aggressive from the first point until the last one, serving good, really focusing on the moment on court," Kerber told reporters.
"I think I was playing good, especially in the second set, it was a little bit close."
The strongly-built six-feet tall Brazilian saved 10 breakpoints in the first set, six of them in the sixth game for a hold, and hit more winners than Kerber. However, she was undone by her erratic shot making.
Haddad Maia cut down on her unforced errors in the second set and made Kerber work harder as the rallies grew longer. The second set went on serve till Kerber broke to go up when Haddad Maia sent a forehand wide.
Another wide forehand groundstroke from the Brazilian gave Kerber the match on the Rod Laver Arena.
"She's also a lefty, so it's always a little bit different to play. Then she was serving good. She really hits the ball hard and tough," Kerber added.
"So I was trying to get a lot of balls back. Also, like I said, being aggressive. I think she's a good player, she really played well."
Former world number one Kerber will next meet Australian wildcard Kimberly Birrell, who earlier ousted 29th seeded Donna Vekic 6-4 4-6 6-1, on Friday while also celebrating her 31st birthday.
"Maybe it's a good omen to play on my birthday," Kerber said. (Reporting by Sudipto Ganguly; editing by Amlan Chakraborty and Christian Radnedge)