Mathews County is a county located in the U.S. state of Virginia. As of the 2020 census, the population was 8,533. Its county seat is Mathews.

Located on the Middle Peninsula, Mathews County is included in the Virginia Beach-Norfolk-Newport News, VA-NC Metropolitan Statistical Area.

During Virginia's colonial era, the area that later became Mathews County was part of Gloucester County. In 1691, the Virginia General Assembly had directed that each county designate an official port-of-entry. Established around 1700, the community of Westville was located along Put-in Creek, a tidal tributary of Virginia's East River feeding into Mobjack Bay, which was a tributary of the Chesapeake Bay.

In 1776 during the American Revolutionary War, Virginia's last Royal Governor, Lord Dunmore, left Virginia after pushed to the southeast to Gwynn's Island by General Andrew Lewis and the Continental Army. General Lewis' forces bombarded Gwynn's Island from Fort Cricket Hill.

In 1791, after Virginia gained its independence from Great Britain, the Virginia General Assembly split Gloucester county and created Mathews County. The county was named for Brigadier General Thomas Mathews, then speaker of the Virginia House of Delegates. Westville was designated at the county seat (later it became known variously as Mathews Court House or simply Mathews).

Seaborne commerce, fishing and oyster farming had always been important in the area and Old Point Comfort Lighthouse was built in 1802 to guide vessels into the Hampton Roads seaport (along with the older lighthouse at Cape Henry). Two additional lighthouses were built slightly later: New Point Comfort Light and Smith Point Light. During the War of 1812, British vessels anchored in Hampton Roads and raided adjacent areas.

Farming was important to the 19th century economy, and early in the century Edmund Ruffin introduced the use of limestone marl as fertilizer on fields worn out from tobacco crops. Two Mathews County men implicated in Gabriel's Rebellion in 1802 were sentenced to transportation out of the Commonwealth. In a lawsuit begun in 1806, Jackey Wright of Mathews County was granted her freedom from prominent landowner Holder Hudgins due to her grandmother's Native American ancestry in one of the last cases decided by Judge George Wythe, with a Virginia Supreme Court opinion by St. George Tucker.

During the American Civil War, many men from Mathews County enlisted in the Confederate Army. Some Union sympathizers petitioned President Abraham Lincoln for help, alleging that Confederate sympathizers had harassed them. Union forces by 1862 controlled the Hampton Roads area and in July 1862 a detachment of Pennsylvania cavalry arrived at Gloucester Court House, then went to Mathews to arrest Carter B. Hudgins, but were unsuccessful. Several other Union raids occurred beginning in September 1863, initially designed to disrupt Confederate salt works. However, in the October 1863 raid, Union General Wistar later reported some of his troops behaved very badly, and Sands Smith was executed after he shot a Union soldier attempting to confiscate his cow. His son and grandson would become prominent Mathews County officials by century's end.