The 2018 United States Open Championship was the 118th U.S. Open, held June 14–17 at Shinnecock Hills Golf Club in Shinnecock Hills, New York, about eighty miles (130 km) east of New York City on Long Island; it was the fifth time the U.S. Open was held at this course.

The United States Open Championship, commonly known as the U.S. Open, is the annual open national championship of golf in the United States. It is the third of the four men's major golf championships, and is on the official schedule of both the PGA Tour and the European Tour. Since 1898 the competition has been 72 holes of stroke play, with the winner being the player with the lowest total number of strokes. It is staged by the United States Golf Association (USGA) in mid-June, scheduled so that, if there are no weather delays, the final round is played on the third Sunday. The U.S. Open is staged at a variety of courses, set up in such a way that scoring is very difficult, with a premium placed on accurate driving. As of 2023, the U.S. Open awards a $20 million purse, the largest of all four major championships.