Peter Lyons was born in Ireland about 1734. He graduated from Trinity College, University of Dublin. Following this, he came to King William County, Virginia, and studied law under his uncle, James Power. He was admitted to the bar on February 5, 1756, and started to practice law in the county courts. On October 20, 1779, Lyons was elected to the general court, which made him an ex-officio member of the Court of Appeals. In 1788, the Court of Appeals was reorganized and the judges, reduced to five in number, were to be elected by a joint ballot of both Houses of Assembly. The first five, elected on December 24, 1788, were Edmund Pendleton, John Blair, Peter Lyons, Paul Carrington and William Fleming. Peter Lyons was elected from Hanover County. In 1789, John Blair left the Virginia Court to become a justice on the Supreme Court of the United States. This left Peter Lyons the second ranking member of the Virginia Court of Appeals, which he presided over in the absence of Pendleton. When Pendleton died in 1803, Lyons succeeded him as President. He maintained this position until his death six years later in Hanover County on July 30, 1809.