Niilo Siren is a 18-year-old professional football player from FIN. He currently plays for Klubi 04 Helsinki, wearing the number 49 shirt. He plays primarily as a Forward.

His most recent move was a from Vantaa to Klubi 04 Helsinki on 2026-01-19.

In the Finland Ykkosliigacup 2026 season, Niilo Siren scored 1 goals and provided 0 assists across 4 appearances, averaging 0.3 goals per game with 0 shots attempted and 0 on target.