 Admitted to the New York bar during 1888, initially John J. McKelvey began to practice law at 10 Wall Street in New York City, with Albert Stickney, Esquire and Edward Morse Shepard, Esquire of Stickney & Shepard, at the top of his bar history; after which, during 1889 John J. associated with DeLancey Nicoll, Esquire.From 1890 to 1894, John J. worked as a solo practitioner at 45 William Street—the same office complex shared by then Grover Cleveland.Between 1894 and 1895, John J. joined the law firm of Shepard, Terry, McKelvey, & Prentiss—a short-lived partnership, though fellow Harvard Law alumni Seth Sprague Terry would subsequently serve John J. as his counsel.