Ken Matsubara was born on 16 February 1993 in Usa, Oita. He came through Oita Trinita's youth ranks before signing with Albirex Niigata in February 2014 and then Yokohama F. Marinos in January 2017. Across nearly a decade at F. Marinos he has been a senior right-back.
With F. Marinos he has won the J1 League in 2019 and 2022, the Super Cup in 2023, and the AFC U23 Asian Cup with Japan in 2015–16. The 2023 season produced 25 J1 matches with 2 goals and an assist; 2024 brought 29 J1 matches with a goal, 2 assists and an Emperor's Cup goal, plus 8 AFC Champions League Elite appearances; the 2025 season has produced 21 J1 League matches.
A 180cm two-footed right-back with the senior leadership presence and tactical understanding of a long-tenured top-flight defender, Matsubara is one of the most experienced J1 right-backs of his generation. He is a candidate for the wider 2026 FIFA World Cup squad as a right-back depth option.