They were the AHL affiliate of the National Hockey League (NHL) Los Angeles Kings during the team's entire existence.

In 1999, Howard Baldwin founded Manchester Hockey Group LLC, while in the process of moving a dormant AHL franchise to New Hampshire to start play in 2001.

[2] Prior to the first game, two members of the Kings organization, Garnet Bailey and Mark Bavis, were killed in the September 11, 2001, terrorist attacks as they were going home back to Los Angeles after a scouting trip.

This continued the streak of first round playoff exits, which the team had experienced in every year of existence, and would come to include the 2005–06 season.

This brought the Monarchs to their first ever Eastern Conference Finals, but they were swept by the defending champions, the Hershey Bears, in four games.

The Monarchs won their home opener of the 2010–11 season, as David Meckler scored the game-winning goal in front of 9,035 fans at the Verizon Wireless Arena on October 16, 2010.

On January 29, 2015, it was confirmed by the AHL via press conference that the Monarchs would relocate from Manchester, New Hampshire, to Ontario, California.

[7] They became the first team since the New Brunswick Hawks in 1982 to win the Calder Cup in their last game of existence, and fourth overall (along with the Pittsburgh Hornets in 1967 and the Buffalo Bisons in 1970).