During the 2018 season, in her junior year, she posted a 23–1 record with a 0.32 earned run average (ERA), and 249 strikeouts in 154 innings, as she led the Wildcats to the Class 2A state championship.

[5] During the 2021 season in her sophomore year, she appeared in 32 games, including 27 starts, and posted a 13–4 record with a 2.08 ERA, 131 strikeouts, and one save in 104 innings.

[9] On May 21, 2021, during the opening round of the 2021 NCAA Division I softball tournament against Alabama State, she recorded a career-high 15 strikeouts in a combined no-hitter.

[10] On May 29, 2021, during the Tuscaloosa Super Regional against Kentucky, she pitched a complete game allowing just one run on five hits, all singles, with seven strikeouts, and helped Alabama advance to the Women's College World Series.

[16] During the 2023 season in her senior year, she appeared in 31 games, including 19 starts, and posted a 16–5 record with a 2.19 ERA and 130 strikeouts in 139+2⁄3 innings.

[19] On May 25, 2023, during game one of the Stillwater Super Regional against Oregon, she retired the final 17 batters she faced, and helped Oklahoma State advance to the Women's College World Series.

[20][21] During the 2024 season in graduate student year, she appeared in 39 games, including 24 starts, and posted a 26–5 record with a 1.20 ERA and 152 strikeouts in 180+2⁄3 innings.

She led the Big 12 in ERA, wins, shutouts (seven), walks allowed per seven innings (1.36), strikeout-to-walk ratio (4.34) and complete games (18), and ranked second in strikeouts (114) and opponent batting average (.172).

[26] Kilfoyl represented the United States at the 2017 Junior Women's Softball World Championship and won a gold medal.

[27] She again represented the United States at the 2019 WBSC U-19 Women's Softball World Cup where she posted a 2–0 record with eight strikeouts, and allowed only two hits in 7+1⁄3 innings and won a gold medal.