He currently plays for Doncaster Rovers, wearing the number 27 shirt. He plays primarily as a Defender. His current market value is estimated at 175K €.

His most recent move was a Free from Crystal Palace U23 to Doncaster Rovers on 2025-07-01.

Throughout the English Football League One 2025-2026, Sean Grehan featured in 17 matches, averaging 0.9 tackles, 0.7 interceptions, and 2.8 clearances per game, while blocking 0.1 shots per game.