Eaker turned senior in 2018. She competed at the American Classic, where she placed first on balance beam, second on floor exercise, and fourth in the all-around. Later in the summer, she competed at the 2018 U.S. Classic, where she placed fifth on balance beam after falling off. At the National Championships Eaker finished seventh in the all-around, second on balance beam behind Simone Biles, fifth on floor exercise, and ninth on uneven bars. As a result of her performance, she was added to the senior national team. The following day, Eaker was named to the team to compete at the Pan American Championships in Lima, Peru alongside Grace McCallum, Trinity Thomas, Jade Carey, and Shilese Jones. On the first day of competition, Eaker won the gold medal on balance beam and the bronze on floor exercise. In the team competition, Eaker contributed on these two events toward the United States' gold-medal-winning performance.