Young Nicholas was educated at home, then read law in Philadelphia where he was admitted to the Pennsylvania Bar in 1765.
Van Dyke entered political life in 1774 as a member of the Boston Relief Committee in Delaware.
He then was a member of the Delaware Constitutional Convention of 1776 and served in the State Council for two years beginning with the 1776–77 session.
That same year he was appointed judge of Delaware's Admiralty Court, and on February 22, 1777, he was elected to the Continental Congress to replace John Evans who had declined to serve.
It was during his tenure as president of Delaware that the American Revolution officially ended with the signing of the Treaty of Paris in September 1783.
His daughter, Nancy Ann, married Kensey Johns at a 1784 wedding in the Amstel House in New Castle that was attended by General George Washington.
Much of the property surrounding Van Dyke's original home Berwick was taken in 1829 for the Chesapeake & Delaware Canal, but the house remained through the American Civil War.