In 1789, he moved to Philadelphia, where he was admitted to the bar in 1792. They had five children. Their son John M. Read was a noted Philadelphia jurist.
In 1797, John Read was appointed by President John Adams as agent general of the United States under the sixth article of Jay"s Treaty, and held that office until its expiration in 1809.
During the yellow-fever plague in Philadelphia in 1793, Read and Stephen Girard remained in the city, and he opened his purse and exposed his life in behalf of his suffering fellow citizens. Read was the author of Arguments on the British Debts (Philadelphia, 1798).
From 1809 to 1815, Read was a member of the city council of Philadelphia. He then served in the Pennsylvania legislature, and in 1816 chairman of its celebrated committee of seventeen.