Atthaya is the third player from Thailand to win the award, after Patty Tavatanakit last year and Moriya Jutanugarn in 2013.
The LPGA Tour handed out year-end silverware at its annual awards show on Thursday in Florida.
The 2022 Player of the Year and money leader will be decided this week at the CME Group Tour Championship.
Atthaya is one of four players in the running, led by favourite and former world No 1 Lydia Ko of New Zealand, who has had a comeback year on tour.
The other two players who can still win Player of the Year are Australian Minjee Lee and Canada’s Brooke Henderson.
Ko leads Lee in the standings by just one point and will clinch the award with a victory at the Tour Championship.
Meanwhile, South Korea’s Chun In-gee won the Founders Award for the player who best embodies "the spirit, ideals and values of the LPGA".
The Annika Major Award for the best performance across all five Majors this season went to Minjee Lee.
She won the US Women's Open, earned a tie for second at the Women's PGA Championship, came 12th at the Chevron Championship and tied for 43rd at the Amundi Evian Championship. She closed out her major season with a tie for fourth at the Women's Open, her fifth top-10 result in nine appearances at the championship.
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