Milmore (Martin) is born in Sligo, Ireland.

Martin Milmore arrives in Boston with his widowed mother and siblings in 1851. He attends public school, graduates from Boston Latin, studies at the Lowell Institute, in the studio of Thomas Ball in Charlestown, and then in Rome. Returning to Boston, he maintains a studio with his brother in the Studio Building at 104 Tremont Street. Daniel Chester French is one of his students. Milmore dies in Roxbury on July 21, 1883, and is buried in Forest Hills Cemetery.