He represented Digby Township from 1785 to 1793 and Annapolis County from 1793 to 1806 in the Nova Scotia House of Assembly.

In the lead up to the outbreak of the American War of Independence, Millidge had been an advocate for non-violent and legal solutions to the grievances of the Thirteen Colonies.

[1] In 1785 he was elected to the Nova Scotia House of Assembly as the first representative for Digby Township, a seat he held until 1793.

In 1806, Millidge was defeated in a bid for re-election to represent Granville Township in the provincial assembly by Isaiah Shaw.

He also served as a justice of the peace, judge in the Inferior Court of Common Pleas and colonel in the local militia.