DelBello was the first Democrat to be elected Westchester County Executive, an office he held from 1974 until 1982, when he stepped down to become lieutenant governor.
He ran for the Democratic nomination for lieutenant governor as the running mate of then Mayor of New York City Ed Koch.
He focused on his role as President of the New York State Senate during his time as lieutenant governor, along with projects of his initiation and Cuomo's assignment.
On March 27, 1984, DelBello served as guest announcer for Late Night with David Letterman.
In December 1984, DelBello surprised political observers by announcing his resignation from the lieutenant governorship, effective February 1, 1985.