He was the co-founder (with John Kearney Rodgers) of the New York Eye Infirmary and the first president of the American Ophthalmological Society.

Delafield was educated at Union Hall Academy before entering Yale University, where he graduated with a Bachelor of Arts in 1812.

He and his brothers Henry, William, and Joseph joined the "Iron Grays", a private infantry company formed in 1814 and charged with protecting New York City from the perceived (but unrealized) threat of a British invasion.

His meticulous handwritten and indexed notes of the lectures he attended, primarily those of Abernethy and Paston, consist of over 3000 pages and are preserved in the New York Academy of Medicine.

In 1825 the first American edition of Benjamin Travers's A Synopsis of Diseases of the Eye and their Treatment was published with additions and extensive notes by Delafield.

He was the first President of the Medical Board of the Nursery and Child's Hospital founded by his niece, Mary Ann Delafield DuBois, in 1854 and served as its consulting physician for the rest of his life.

They married in 1839 and had five children, including:[11][12] In 1859, Dr. Edward Delafield and his second wife Julia Floyd bought their initial 50 acres of land in Darien, Connecticut for $6,000.

They continued to buy neighboring plots around the main house and eventually amassed 165 acres on Scott's cove.

He was buried in Green-Wood Cemetery with the last two of his surviving brothers, Joseph and Henry, following a joint funeral at Trinity Church in New York City.