Pleasants was born at “Cold Comfort,” in Powhatan County, Virginia, October 24, 1769. He pursued classical studies and graduated from the College of William and Mary, Williamsburg, Virginia. He studied law and was admitted to the bar and commenced practice in Amelia County, Virginia in 1791. He was a member of the Virginia House of Delegates 1797-1802 and clerk of the house of delegates 1803-1811. Pleasants was elected as a Democratic Republican to the Twelfth and to the four succeeding Congresses and served from March 4, 1811, to December 14, 1819, when he resigned, having been elected a United States Senator. Pleasants served as chairman of the Committee on Public Expenditures (Thirteenth Congress), Committee on Expenditures in the Department of the Navy (Fifteenth Congress). He was elected on December 10, 1819, as a Democratic Republican to the United States Senate to fill the vacancy caused by the resignation of John W. Eppes and served from December 14, 1819, to December 15, 1822, when he resigned. He was also chairman of the Committee on Naval Affairs (Sixteenth and Seventeenth Congresses). He was chosen as Governor of Virginia, serving 1822-1825. Pleasants was a delegate to the State constitutional conventions in 1829 and 1830. He retired and lived on his estate, “Contention,” near Goochland, Goochland County, Virginia, where he died on November 9, 1836. He was buried on his estate.

His good friend, Henry Massie, names his son James Pleasants Massie, after Pleasants. The name has been handed down, now to a total of four generations.