McIlroy fired his fourth straight sub-70 round at Congressional Country Club in Maryland, carding a 2-under 69 on the final round to shatter the U.S. Open's previous low total mark by four shots.
The 22-year-old finished eight shots ahead of Australian Jason Day (68), set or tied 12 records along the way and became the youngest person to win the U.S. Open since World War II.
The win was especially sweet after McIlroy blew a four-shot lead two months ago on the final day of the Masters.
Kevin Chappell (66), Robert Garrigus (70), Lee Westwood (70) and Y.E. Yang (71) all knotted for third place at minus-6.