On July 3, 2015, MacWilliam signed as a free agent to a one-year, two-way contract with the Winnipeg Jets.

[2] On July 1, 2016, as a free agent for a second consecutive season, MacWilliam left the Winnipeg Jets to sign a one-year, two-way deal with the New Jersey Devils.

[3] On July 4, 2017, having left the Devils as a free agent, MacWilliam with slim NHL interest opted to continue in the AHL, signing a contract with the Rochester Americans, affiliate to the Buffalo Sabres.

[4] With the following 2020–21 North American season delayed due to the COVID-19 pandemic, MacWilliam opted to pursue a career abroad, agreeing to an initial try-out with German three-time champions, EHC München of the DEL.

[7] In July 2024, MacWilliam agreed terms to join UK EIHL side Cardiff Devils.