The Horsemen were first announced by owner Chris Reynolds in late 2017, with the expressed interest in joining either the
Indoor Football League or
Champions Indoor Football. However, due to instability with both leagues, Reynolds took a "wait-and-see approach" before making a decision with the intent to start play in 2019. On October 15, 2018, the Horsemen announced that they had started their own league, the
American West Football Conference, and added three other teams to the league, the
Reno Express, the
Tri-Cities Fire, and
Wenatchee Valley Skyhawks. On March 23, 2019, the Idaho Horsemen played their first game at the Ford Idaho Center in front of 2054 spectators against the Wenatchee Valley Skyhawks. The Horsemen scored on their first drive in five plays on a run by quarterback Hayden Wright. The Horsemen went on to win 33–22. The Horsemen went undefeated in their first season at 12–0 and earned the right to host the AWFC championship game. They defeated the Reno Express 40–20 to win the league championship. Prior to the planned start of the 2020 AWFC season, the
Tri-Cities Fire folded leading to the Horsemen announcing they would play an independent schedule. The league then tried to move forward with three teams — Idaho, Wenatchee, and the expansion Yakima Canines — following the withdrawal of the Reno Express from the league with non-league teams filling for the newly vacant dates. The AWFC then postponed the 2020 season due to the ongoing
COVID-19 pandemic and then cancelled the season entirely due to the unavailability of arenas during the pandemic. After winning the 2023 AWFC championship, the Horsemen were announced as joining the
National Arena League (NAL) for the 2024 season. After the 2025 season, the Horsemen announced that they would not return to the Ford Idaho Center for 2026, but have made it clear they will stay in the league as they search for a new home outside of Idaho. In a September 19, 2025, press release from the NAL, the Horsemen were announced to be going dormant for 2026 and indications are that the team will be relocating to Arizona. ==Season-by-season records==