Walter Livingston combined the work of a merchant and lawyer with public service in revolutionary New York. He served as an Albany County judge and attended the provincial convention of April and May 1775, followed by the first Provincial Congress. In July 1775 he became commissary of stores and provisions for the New York department. His supply work in the northern theatre continued into 1776, when he resigned, helping sustain the Continental forces.

Under New York's new state government, Livingston sat in the Assembly from 1777 to 1779 and became its first Speaker. He helped establish the procedures of the legislature while the state remained a major theatre of war. He later returned to the Assembly in the 1780s. His public responsibilities also included service on the commission dealing with the boundary between New York and Massachusetts in 1784, a dispute involving competing territorial claims and settlement.

Livingston represented New York in the Confederation Congress in 1784 and 1785. Appointed a commissioner of the United States Treasury in 1785, he participated in the financial administration of the government before the federal Constitution established the later Treasury Department. He also served as a regent of the University of the State of New York from 1784 to 1787. His estate at Teviotdale remained part of his adult life alongside these appointments. He died in New York City in 1797 and was buried in Trinity Churchyard.