Horseman joined Southampton in August 2019 after coaching Bristol City and Watford.
[3] On 17 July 2023, he was appointed as head coach of Forest Green Rovers, replacing caretaker manager Hannah Dingley.
[7] On 20 December 2023, Forest Green Rovers parted ways with him by mutual consent.
[8] On 1 July 2024, Horseman was appointed first-team coach at League One side Bristol Rovers.
[9] In December 2024, following the sacking of manager Matt Taylor, Horseman was appointed caretaker manager alongside fellow first-team coach Lee Cattermole.