The world number two, who served a one-month doping suspension last year and lost her top ranking to Aryna Sabalenka, beat the 46th-ranked Czech 6-3, 6-4 on John Cain Arena.
“For sure it wasn’t an easy first round. So I’m happy that I’m through,” said the Pole.
She will face 49th-ranked Slovakian Rebecca Sramkova in the second round.
It wasn’t all plain sailing against the doubles specialist Siniakova.
Second seed Swiatek appeared to be cruising at 4-2 and 40-0 up in the first set when Siniakova suddenly found another gear to break back.
Swiatek berated herself and came out aggressively after the changeover to break Siniakova again and serve out for the set in 38 minutes.
Swiatek edged 2-0 in front at the start of the second but again the nine-time doubles Grand Slam champion managed to get back on serve.
Another break gave Swiatek the edge once more and this time she closed out the match in 81 minutes.
“Katerina, I know her from playing doubles against her that she’s not an easy opponent,” admitted Swiatek.
“She was playing really well and I just needed to be more proactive. I did that in the second set, so I’m happy.”
The 23-year-old Swiatek has never shone at Melbourne Park.
She has only progressed beyond the fourth round at the Australian Open in 2022, when she was upset by Danielle Collins in the semi-finals.
Swiatek began her 2025 campaign with four singles wins out of five in the United Cup, her first event since it was revealed she had served a doping suspension.
Swiatek pulled out of the WTA’s late-season Asian swing citing “personal matters”.
Later it emerged she had been under a one-month suspension for testing positive for a banned heart medication. She denies knowingly doping.
The Polish star has fourth seed Jasmine Paolini, sixth seed Elena Rybakina and eighth seed Emma Navarro lurking in her half of the draw.
But she cannot face the world number one and defending champion Sabalenka until the final, should she get that far.
© 2025 AFP