She won the gold medal in the 800 meters at the 2022 World Under-20 Championships, adding second title for the women's 4x400 m relay.

Her mother is Irish track athlete Breeda Dennehy-Willis, who competed at the 2000 Sydney Olympics.

[2] After graduation from high school, she attended Stanford University, where she participates in cross country and track and field.

[9] As a freshman at Stanford, Willis won the 800m in a time of 1:59.93 at the NCAA Indoor T&F Championships in Albuquerque, NM, setting a personal best, and meet and facility records in the process.

Following her freshman year, she signed an NIL deal with New Balance prior to competing at the US Track and Field Championships.