Cushing represented Massachusetts in the First (during which he signed the Continental Association) and Second Continental Congresses but was voted out when he opposed independence. Despite this, he remained politically active after independence, continuing to serve in the state government. During the Revolutionary War, he was a commissary responsible for provisioning the military, a position he used to enrich the family merchant business. He was elected the state's first lieutenant governor in 1780. Politically associated with fellow merchant Governor John Hancock, he remained lieutenant governor until his death in 1788, briefly serving as acting governor in 1785 between the resignation of Hancock and the election of James Bowdoin.