West Coast Eagles assistant coach (2010-2017) Longmuir was appointed as an assistant coach in the role of development coach of the
West Coast Eagles under senior coach
John Worsfold at the end of the
2010 season. At the end of the
2011 season, Longmuir switched his assistant coaching position to the role of forward coach, replacing
Peter Sumich, who switched to Longmuir's former club, Fremantle. Longmuir then spent seven years as an assistant coach at West Coast Eagles, including under senior coach
Adam Simpson, who replaced Worsfold at the end of the
2013 season. Longmuir left the West Coast Eagles at the end of the
2017 season.
Collingwood Football Club assistant coach (2017-2019) At the end of the 2017 season, Longmuir was appointed as an assistant coach in the role of the defence coach at
Collingwood under senior coach
Nathan Buckley.
Fremantle Football Club senior coach (2020–present) In September 2019, after nine years as an assistant coach with both West Coast and Collingwood, Longmuir was appointed senior coach at his former club , replacing caretaker senior coach
David Hale, who replaced
Ross Lyon during the 2019 season with one game left to go. Longmuir's first season as senior coach was during the shortened
COVID-19-affected
2020 AFL season. Fremantle under Longmuir finished twelfth on the AFL ladder with seven wins and ten losses and did not make the finals. The
2021 AFL season saw the Dockers under Longmuir finish eleventh place on the ladder, with ten wins and twelve losses. He signed a two-year contract extension at the season's end. In the
2022 AFL season, Longmuir guided the Dockers to fifth position on the ladder and a return to finals for the first time since 2015. Fremantle under Longmuir defeated and eliminated the
Western Bulldogs in the elimination final, but the Dockers were however eliminated by
Collingwood in the semi finals. The
2023 AFL season saw Fremantle under Longmuir finish 14th on the ladder with 10 wins and 13 losses. Already contracted until the end of 2024, Longmuir signed a one-year contract extension in March 2024, tying him to Fremantle until at least the end of 2025. The Dockers hosted an elimination final against the
Gold Coast Suns, losing by one point. Following the 2025 season, Longmuir entered into an ongoing employment agreement with Fremantle. ==Personal life==