Joshua Henshaw was born in Boston and entered the mercantile profession at an early age. He rose to a position of social influence following his marriage to Elizabeth Bill, the daughter of a prosperous merchant. He served frequently as town magistrate and served on various town committees with figures such as John Hancock and Samuel Adams. While Henshaw never achieved the fame of some of his fellow patriots, he did manage to use his position to protest British rule and to advance the American colonists' rights.