Zmeskal was unable to defend her American Cup title, losing to Okino by a margin of just .225 points, but won the event finals for beam and floor. She then defended her U.S. National All-Around title in Cincinnati, where she also won the national title on floor alongside Dominique Dawes and placed second on beam. At the 1991 World Championships in Indianapolis, she helped the team win the silver medal, the first team medal for the American women in World Championship history, beating out the Romanians to finish second behind the Soviet Union. She scored a perfect 10.000 on the vault in the final rotation of the optional rounds, one of only two perfect 10's at the championships, and becoming the first (and only) American woman to ever score a perfect 10 at the World Championships. Zmeskal also became the first American to win the World all-around gold medal, posting scores of 9.962 on the vault, 9.937 on uneven bars, 9.962 on the beam, and 9.987 on the floor to defeat reigning world champion Svetlana Boginskaya with a total score of 39.848. She also won bronze on the floor and placed seventh on vault in the event finals.