He served as general manager of the Economic Development Corporation of the City of Dieppe, New Brunswick and as a business executive.

[2] On September 6, 2017, in a cabinet shuffle, Melanson was named Minister of Treasury Board and Post-Secondary Education.

[3] From October 5, 2018 to November 9, 2018 Melanson served as Minister of Energy and Resource Development.

On September 28, 2020 he was chosen as interim leader of the opposition Liberal party of New Brunswick, replacing Kevin Vickers who had resigned following the provincial election of September 14.

[4] He remained interim leader until August 2022,[5] when Susan Holt won a party leadership election in which Melanson was not a candidate.