Objective <p>This study aimed to investigate the effect of stress ball use during the non-stress test (NST) on anxiety and fetal well-being in high-risk pregnant women.</p> Method <p>A randomized controlled pretest-posttest study was conducted with 86 high-risk pregnant women undergoing NST in a public hospital in northern Türkiye. Participants were randomly assigned to intervention (<i>n</i> = 43) and control (<i>n</i> = 43) groups. The intervention group used a stress ball during the NST procedure, while the control group received routine care. Data were collected using a Personal Information Form, the State Anxiety Inventory (SAI), and a Fetal Well-Being Assessment Form. Statistical analyses included t-tests, Mann-Whitney U tests, Chi-square tests, Wilcoxon tests, and two-way ANCOVA.</p> Results <p>The intervention group had significantly lower posttest anxiety scores (35.56 ± 6.55) than the control group (40.05 ± 6.82) (<i>p</i> = 0.003), with a significant within-group decrease of 9.49 points (<i>p</i> = 0.000). Moreover, fetal movement count and basal fetal heart rate increased significantly in the intervention group compared with the control group (<i>p</i> = 0.002 and <i>p</i> = 0.005, respectively). These changes were also significant within the intervention group (<i>p</i> = 0.000).</p> Conclusion <p>Stress ball use during NST may be associated with short-term improvements in fetal well-being indicators and maternal anxiety. It is recommended as a simple, low-cost, noninvasive, and drug-free intervention in prenatal care.</p> Clinical trial number <p>NCT06302010 (Registration Date: 02.10.2024).</p>