In August, Mikulak won his fifth national all-around title in dominant fashion at the 2018 U.S. National Championships in Boston. After a somewhat shaky performance on Day 1 that included falls on pommel horse and high bar, he came back with a very strong outing on Day 2 and won the gold medal easily. His margin of victory was the largest of any of his national titles at the time (he would extend this record in 2019). He also won the gold medal on floor exercise, parallel bars and high bar. Mikulak is the first male gymnast to win five U.S. national titles since Blaine Wilson won five straight crowns from 1996 to 2000.