He competed for the United States in the 1936 Summer Olympics held in Berlin, Germany, in the 4 × 400 meter relay, where he won the silver medal with his teammates Harold Cagle, Robert Young and Alfred Fitch.

He enlisted in the United States Navy in December 1941, serving on a destroyer in the South Pacific.

He had one child, Edward T. O'Brien Jr., a psychologist who resides in Clearwater, Florida.

O'Brien died on September 15, 1976, of colon cancer after living for several years at his home in Bermuda.

This article about a track and field Olympic medalist of the United States is a stub.