Kiara Fontanilla

Fontanilla played for the varsity women's football (soccer) team of Norco High School under head coach Daniel Graffa. She was a two-year varsity letterwinner. In her senior season in 2017, she led her team to the California Interscholastic Federation. She also played for local soccer club Arsenal FC where she helped make it to six consecutive editions of the Surf Cup from 2013 to 2018.

As a freshman, Fontanilla played for the Northwestern Oklahoma State Rangers. She became part of the Cal State Fullerton Titans women's soccer team for the 2019 season. She redshirted for her sophomore season. She was part of the Titans squad which won the Big West regular season Conference Championship and Tournament Championship. In the 2020 season, she joined the Eastern Oregon Mountaineers. In 2022, she transferred to a school in Southern California so she could focus on her club soccer career.

In 2023, Fontanilla began playing for the Central Coast Mariners. She is a top-ranked goalkeeper in the FNSW Women's League One. Fontanilla entered the 2024 draft for the National Women's Soccer League.

Manila Digger

In July 2024, after weeks of training with the team, the club officially announced the signing of the Philippines international goalkeeper, along with compatriot Rhea Chan.

Fontanilla was born in Fullerton, California to a Mexican mother, Fabiola (née Reyes), and a Filipino father, Francisco Fontanilla but was raised in Jurupa Valley and Eastvale. Her father has roots in Baguio having moved to the United States at age seven. She attended Norco High School where she graduated in 2018. She attended the Northwestern Oklahoma State University for her freshman year before moving to the California State University, Fullerton the following year. She then moved to the Eastern Oregon University in 2020.