Background
He was born in Brooklyn, Kings County, New York, the son of Keran O'Brien and Florinda O'Brien.
politician member of the New York State Senate
He was born in Brooklyn, Kings County, New York, the son of Keran O'Brien and Florinda O'Brien.
He engaged in the real estate and insurance business. O'Brien was elected on January 9, 1930, to the New York State Senate (9th D) to fill the vacancy caused by the resignation of Charles E. Russell. He took his seat the same day, and remained in the State Senate until his death in 1935, sitting in the 153rd, 154th, 155th, 156th, 157th and 158th New York State Legislatures.