He is on the books of Barendrecht and wears shirt number 19. His main role on the pitch is Forward. His stronger foot is Right.

His latest transfer saw him join Barendrecht from HV CV Quick via on 2024-07-01.

During the Netherlands Tweede Divisie 2025-2026 campaign, R. van Mierlo made 9 appearances, scoring 0 goals and adding 0 assists. He averaged 0 goals per match from 0 shots, with 0 on target.