McDonald turned professional after graduating from college in 2015. She finished T-22 at the
LPGA Final Qualifying Tournament to earn a conditional
LPGA Tour card for 2016. She played primarily on the
Symetra Tour in 2016, finishing runner-up four times and finishing second on the money list. She has played full-time on the LPGA Tour since 2017. In 2019, she was named to the
2019 Solheim Cup team to replace an injured
Stacy Lewis. In October 2020, McDonald won the
LPGA Drive On Championship. This was her first LPGA victory. The tournament was a new event, created in 2020 due to the cancellation of Asian events as a result of the
COVID-19 pandemic. McDonald started using her married name, Ally Ewing, in late 2020. In May 2021, Ewing won the
Bank of Hope LPGA Match-Play at
Shadow Creek Golf Course in
North Las Vegas, Nevada. She went 6–1–0 for the week and defeated
Sophia Popov in the final match, 2 & 1. In September 2022, Ewing would make five birdies on the back nine en route to win the
Kroger Queen City Championship. In November 2024, Ewing won
Founders Award. Ewing retired following the 2024 season. ==Professional wins (3)==