In 1977 he opened his own gallery on Fifth Avenue in New York City with his wife, Betsy Wittenborn Miller; it later moved to the Fuller Building on East 57th Street, and then to 26th Street in Chelsea, Manhattan.He showed work by the artists Louise Bourgeois, Lee Krasner, Joan Mitchell and Alice Neel, and by photographers such as Jan Groover, Robert Mapplethorpe and Bruce Weber.He retired in 2002, and died on June 22, 2011, aged 72, at his home in El Portal, Florida, from an infection.
Patti Smith reflecting on her friend Robert Mapplethorpe thought Miller was a mentor to him.