He was born in Paris, France to George Henry Warren I (November 8, 1823 - April 8, 1892) and Mary Caroline Phoenix (February 27, 1832 - January 18, 1901). His brothers were Whitney Warren (of Warren & Wetmore, one of the most prestigious American architecture firms) and George Henry Warren II, a stockbroker.
- "Sleep-Walk Plunge Kills Lloyd Warren; Famous Architect Falls From His Sixth-Floor Apartment in Early Morning. Suicide Theory Discarded. Victim Had Suffered From Somnambulism. Created BeauxArts Institute". New York Times. October 26, 1922. Retrieved 2010-07-25.
Lloyd Warren, architect, was found dead yesterday morning in an areaway below his bedroom at 1 West Sixtyfourth Street. It is believed that he fell accidentally while opening the window of his apartment, which is on the eighth floor. Mr. Warren who was founder of the Beaux-Arts Institute of Design, and a brother of Whitney Warren, the architect, ... Subject to Sleep-Walking. Not a Suicide, Says Doctor.
- "Tribute to Lloyd Warren". Magazine of Art. 1922.
This Institute that he founded less than a decade ago is and will remain, in the opinion of its countless friends, the very best monument that could be erected to Lloyd Warren's memory. ...