Hilary, 22, and 29-year-old Mike tied the knot at the at the San Ysidro Ranch in Santa Barbara, California, according to In Touch.
Hilary wore a strapless Vera Wang gown, and had her sister and BFF Haylie Duff as her maid of honour.
A source said "it was one of the most beautiful weddings I've ever seen. Absolutely stunning. They thought of every last detail and it was an incredible sight."
The pair got engaged in February while on holiday in Hawaii and they are set to marry in the ranch where John F. Kennedy and wife Jacqueline spent their honeymoon.
An insider said to the magazine that they chose the location because of "its sense of Old Hollywood glamour and romantic style".