The Polish world No. 1 eased past Garcia 6-3 6-2 in 83 minutes on Thursday to win her second straight match at the eight-player event in Fort Worth, Texas, news outlets reported.
Świątek opened her WTA Finals campaign with a 6-2 6-3 victory over Russia's Daria Kasatkina.
She will now take on American Coco Gauff in her last group-stage match on Saturday.
The 2022 WTA Finals event runs in the southern United States until November 7.
The Polish tennis star last month won the San Diego Open tournament in the United States, claiming her 11th career singles title.
Świątek in September won the US Open, capturing her third Grand Slam trophy.
The 21-year-old, coached by countryman Tomasz Wiktorowski, in early April took over as the new world number one in women's tennis, becoming the first Pole to top the Women's Tennis Association (WTA) rankings.
She now leads the WTA world rankings with 10,335 points, ahead of Tunisia's Ons Jabeur, with 4,555 points, and American Jessica Pegula, with 4,316 points.
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Source: IAR, PAP, wtatennis.com