Aim <p>This study was conducted to explore the effect of stress ball use on pain, sleep quality and physiologic parameters in critically ill patients.</p> Methods <p>A prospective, two-arm randomized controlled trial was performed in the intensive care units (ICUs) of a training and research hospital in Turkey. Study participants were randomly assigned to either a control group or a stress ball group. The outcome measures were pain, sleep quality (RCSQ) and physiological parameters.</p> Results <p>Thirty patients in each group completed the study. A statistically significant difference was found between the groups at 07:00 on ICU day 3 (T3), with lower pain intensity in the stress ball group (<i>p</i> &lt; <i>0.05</i>). The difference in RCSQ scores between the two groups was found to be statistically significant, with higher RCSQ scores observed in the stress ball group (<i>p</i> &lt; <i>0.05</i>). No significant differences were found between the groups heart rate across all measurements and respiration rate at any time point except 19:00–23:00 (T4), whereas diastolic blood pressure differed significantly at all measurements and systolic blood pressure showed significant group differences at 13:00–17:00 (T3) and 19:00–23:00 (T4) (<i>p</i> &lt; <i>0.05</i>).</p> Conclusion <p>The findings of this study indicated that the use of a stress ball was associated with improved sleep quality and significant reductions in pain intensity, systolic and diastolic blood pressure in critically ill patients.</p>