He is on the books of Ross County and wears shirt number 3. His main role on the pitch is Defender. His estimated market valuation currently stands at 75K €.

His latest transfer saw him join Ross County from Glenavon Lurgan via on 2025-07-04.

Across the Scottish Championship 2025-2026, Len O'Sullivan appeared in 26 matches and averaged 0 tackles, 0 interceptions, 0 clearances, and 0 blocked shots per game.