During the third round of the 2017 U.S. Open at Erin Hills, Thomas equalled the U.S. Open single-round record of 63. He eagled the last hole by hitting his 3-wood to 8 feet on the par-5 hole to finish at 9-under-par, also a U.S. Open record, passing the previous record held by Johnny Miller at Oakmont Country Club. In the fourth round, he played alongside Brian Harman in the final grouping, the first time he had done that in a major championship. He shot a three-over-par 75 and finished in a tie for ninth place.