Kokkinakis, who underwent radical surgery last February in a bid to fix a long-standing pectoral problem, downed American Sebastian Korda at the Adelaide International on Monday night.
After fellow Australian Alexei Popyrin departed the tournament with another first-round loss - his second such exit in a week - a hobbled Kokkinakis triumphed 3-6 6-3 7-6 (7-3).
Kokkinakis, in his first singles outing since January 15 last year, played through pain to courageously finish his comeback match.
But he frequently received medical treatment, casting doubt on any appearance at the Australian Open starting Sunday.
The 29-year-old has a protected ranking to enter the singles at Melbourne Park, where he's also scheduled to play doubles with Nick Kyrgios.
Last February, Kokkinakis had a dead person's Achilles tendon attached to his right pectoral muscle and shoulder.
The first tennis player to undergo such surgery, he made his competitive return in doubles with Kyrgios last week at the Brisbane International.
But the injury flared during his singles comeback after a raucous reception walking on to centre court in his home town.
Kokkinakis sent down first serves consistently around 195kmh in the opening set.
World No.51 Korda took the set before Kokkinakis raced to a 3-0 advantage in the second when his injury resurfaced.
Grimacing and feeling his shoulder, he called a medical timeout.
At 4-1, the 29-year-old again received massage treatment at the change of ends yet defied his pain to break Korda's serve in the next game.
Adopting daringly aggressive tactics in a bid to shorten rallies, Kokkinakis ultimately won the set 6-3 despite his service speed dropping about 20kmh.
Korda appeared prepared for Kokkinakis to retire when the Australian left the court - but he returned for the third set, when almost every rally ended with the Australian clutching his shoulder.
The set went to a tiebreak, in which Kokkinakis somehow produced one 196kmh serve as he closed out a remarkable victory.
Earlier, Popyrin remained bullish despite consecutive first-round exits to start his new tennis year.
Red-hot American Reilly Opelka outgunned the Australian, pounding 22 aces in his 6-3 7-6 (8-6) triumph.
Popyrin's straight-sets loss followed his defeat last week in the first round at the Brisbane International to French qualifier Quentin Halys.
But the world No.49 was adamant the signs aren't all doom and gloom ahead of the Australian Open.
"Everything that we've been doing is good and it's working," Popyrin said.
"It might not be showing in the first two weeks of the year but I'm looking forward to the AO. I think I can do some stuff there.
"Physically, mentally, I'm feeling the best I have felt in a long time ... it's only a matter of time before results will come."
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