Monaghan vs. Trigueno

Monaghan made his professional debut in his hometown. He faced Simeon Trigueno. A body shot sent Trigueno down to a knee for an eight count. He beat the count but was dropped again by a straight right hand to the head and was saved by the bell to end the round. The ringside doctor put an end to the bout citing an injury. Monaghan was credited with a first-round TKO.^[4]

Monaghan vs. Pietrantonio

Monaghan scored a fifth-round TKO over Anthony Pietrantonio in the Garden's WaMu Theatre on October 22, 2011.^[5]

Monaghan vs. Johnson

On June 14 in front of a capacity crowd at NY's Roseland Ballroom, Monaghan became the new WBC Continental Americas Light Heavyweight Champion with an 8th-round TKO over Romaro Johnson^[6]

Monaghan has been working on sharpening his technique with greater emphasis on speed, head movement and combination work as opposed to merely looking to land the devastating kill shot, although he still possesses a keen ability to score knockouts.^[7]

Monaghan vs. Cantrell

Monaghan appeared on the undercard of the WBO featherweight championship fight between Orlando Salido and challenger Mikey Garcia at Madison Square Garden Theater on January 19, 2013, where he defeated Roger Cantrell by unanimous decision in an eight-round fight.^[8]

Monaghan vs. Stanley

On the April 13th Donaire-Rigondeaux undercard at The Radio City Music Hall Monaghan scored a first-round knockout of journeyman Dion Stanley (overhand right). This knockout propelled his career - convincing Top Rank Boxing's Bob Arum to sign the popular fighter.^[9]

Monaghan vs. Barrera

Monaghan was defeated by Sullivan Barrera via unanimous decision in their 10-round contest on 3 November 2018. The scorecards were announced as 99–91, 99–91, 98–92 in favor of Barrera.^[10]

Monaghan vs. Johnson

In his next bout, Monaghan faced Callum Johnson, ranked #15 by the IBF at light heavyweight. Johnson beat Monaghan by technical knockout in the 3rd round.^[11]