Yokoyama was born in Tama on August 13, 1993. After graduating from Jumonji High School, she joined Okayama Yunogo Belle in 2012. In 2014, she moved to Nadeshiko League Division 2 club AC Nagano Parceiro. She became top scorer in 2014 and 2015. The club was also promoted to Division 1 from 2016. In 2016 season, she was selected Best Eleven. In July 2017, she moved to German Bundesliga club Frankfurt. In July 2018, she returned to AC Nagano Parceiro. In 2020, she moved to Washington Spirit.