On 11 March 2015, Muldoon agreed a new contract with Charlton, signing until 2017 and being immediately loaned to Gillingham until the end of the season.[5] He made his first-team debut three days later, starting in a 0–0 away draw against Bristol City in League One.[6]
Muldoon was released by Charlton on 1 February 2017.[8] He rejoined Gillingham on 21 February for the remainder of the 2016–17 season,[9] but was released by the club at the end of the season after just four appearances.[10][11]