The 22-year-old recorded a 6-4 6-3 opening-round victory over Sloane Stephens at the Guadalajara Open and will next face another American in second seed, and world No.11, Danielle Collins.
In continues a good run for Gadecki in 2024.
This is her fifth career WTA main-draw success and first since the Brisbane International in January.
It is also her third career top-100 victory and comes after securing doubles titles in Austin and Charleston with Brit Olivia Nicholls.
Main draw win number ✌️— wta (@WTA) Olivia Gadecki picks up a big win and moves into Round 2!#GDLOpenAKRONxSantander pic.twitter.com/NmP45IhM9lSeptember 9, 2024
It was the third career meeting between Gadecki and Stephens, all of them taking place this year.
Stephens, the 31-year-old former world No.3 and 2017 US Open champion, got the win at the Australian Open but was forced to retire in their next match in Paris.
After losing in US Open qualifying and the quarter-finals of the WTA 125 event also in Guadalajara last week to Germany's Tatjana Maria, Gadecki beat compatriot Maya Joint in straight sets in qualifying.
The current world No.152, who enjoyed a career-high ranking of 120 earlier this year, fired down six aces to her opponent's none in her 85-minute win on Monday (Tuesday AEST).
"It really means a lot hearing my name out from the crowd," Gadecki said.
"So yeah, thank you again, muchas gracias."
There were eight breaks of serve during the match, with the Gold Coast right-hander snatching five of her 12 opportunities.
Fellow Australian Kimberly Birrell gets her campaign underway against fellow qualifier Ena Shibahara of Japan on Tuesday (Wednesday AEST).
In other matches, seventh-seeded Kazakh Veronika Kudermetova saw off American lucky loser Sachia Vickery 6-4 6-4 and Russia's Kamilla Rakhimova beat Aleksandra Krunic of Serbia 7-5 6-0.
There were also round-one wins for local Renata Zarazua and Colombia's Camila Osorio.
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