Inglis, a 24-year-old from Perth, needed just 82 minutes on Tuesday to wrap up the 6-4 6-2 victory over No.23 seed Fernandez, who made it all the way to the unlikeliest of title deciders at Flushing Meadows last year against British qualifier Emma Radacanu.
After racing to a 4-0 lead in the second set, Inglis held her nerve in a marathon sixth game, saving several break points before sealing it with an ace.
Two games later she finally wrapped up her first victory at a grand slam at her fifth attempt, setting up a second-round encounter against US qualifier Hailey Baptiste.
"I had thought about that moment for a long time," said Inglis, who made her grand slam debut as a teenager at Melbourne Park back in 2016.
"It was just pure happiness when I saw the ball go out.
"It was an amazing moment.
"I'm really so happy I could have it happen here in Melbourne with all my friends and family there."
Inglis was joined in the second round by one of her childhood idols Samantha Stosur, who fully justified the decision to award her a wildcard for her record 20th and final Australian Open at the age of 37 by ousting American Robin Anderson 6-7 (5-7) 6-3 6-3.
."Sam and Ash (Barty) are both amazing people and amazing role models," said Inglis.
"We're pretty lucky to have those girls as people to look up to as Aussie tennis players."
It was only Stosur's second victory in her past seven visits to Melbourne Park, a venue where she has never progressed beyond the fourth round.
"That was incredible," said the Queenslander, who is now ranked 487th in the world.
"That's a match I'm gonna remember forever."
Fellow wildcard Chris O'Connell advanced to round two for a second successive year by downing Frenchman Hugo Gaston in four sets.
The 27-year-old Sydneysider won 7-6 (7-4) 6-0 4-6 6-1 to set up a clash on Thursday with Argentinian No.13 seed Diego Schwartzman.
The late-blooming O'Connell had a rollercoaster 2021, mixing some good results with an ankle injury, osteitis pubis and a bout of coronavirus.
"My very first tournament back I caught COVID, which has knocked me around for a little bit so, yeah, that was my year - good results and injuries and sickness," he said.
Aleksandar Vukic also vindicated the decision to hand him a wildcard by beating No.30 seed Lloyd Harris on Monday.
Playing in her first major since last year's Australian Open and having recovered from surgery to the Achilles tendon that had troubled her on and off for five years, Daria Saville lost 6-2 6-3 to Swede Rebecca Peterson.
Jordan Thompson was on the wrong end of a five-set marathon against American Steve Johnson, losing 7-6 (7-5) 6-7 (6-8) 4-6 6-3 6-3.
Priscilla Hon bowed out of the women's event with a 6-2 6-3 loss to Czech No.31 seed Marketa Vondrousova, while Astra Sharma succumbed 6-3 6-4 to Dane Clara Tauson.
AUSSIES IN ACTION ON DAY THREE OF THE AUSTRALIAN OPEN ON WEDNESDAY: (PREFIX DENOTES SEEDING):
Women's singles, second round:
1-Ash Barty v Lucia Bronzetti (ITA)
Men's singles, second round:
John Millman v 3-Alexander Zverev (GER)
Aleksandar Vukic v Radu Albot (MDA)
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