Watson, who reached the third round Down Under last year before suffering an illness-hit 2013, defeated Irina Falconi of America 6-4, 7-6 in the third and final round of qualifying.
I’ve just got over that first hurdle and there’s a long way to go yet
She now joins fellow Brits Andy Murray and Laura Robson, who won Olympic mixed doubles silver together at London 2012, in the main draw with Daniela Hantuchova first up.
And Watson revealed the extent to which she would have been devastated had she not progressed out of qualifying and booked a clash against the Slovakian No.31 seed.
“It would have been the end of the world if I didn’t get through,” said Watson. “I’m very happy that I am through but this is where it starts.
“I’ve just got over that first hurdle and there’s a long way to go yet. It was a very tricky match. She’s not you’re usual WTA player.
“She slices a lot, she’s got good hands, good touch, she’s not the overpowering type.
“I was prepared for it but I was torn between, ‘Do I go for it, or do I make her play?’
“I was finding it difficult to find the balance but I held my nerve at the end, at the very end.
“I got a bit nervous closing it out but it’s last round of qualifying; there’s a lot on that match.”