Aromatherapy has been proposed as a non-pharmacological strategy capable of modulating psychophysiological responses that may influence athletic performance; however, evidence regarding its acute effects on swimming performance remains limited. The aim of this study was to examine the acute effects of different olfactory essential oils on 50-m sprint swimming performance in competitive swimmers. Twenty-one competitive sprint swimmers (8 males/13 females; age: 21.9 ± 2.0 years) completed four experimental conditions separated by four days: control (CON); activation essential oil (ACT); relaxation essential oil (REL); and placebo (PLA). Following a standardized warm-up, participants were exposed to the respective olfactory stimulus and subsequently performed a maximal 50-m sprint swim. Sprint time was recorded using a partially randomized within-subject crossover design. No statistically significant overall effect of condition on sprint performance was observed [F (3,57) = 2.762, p = 0.062]. A small reduction in sprint time (~1.2 %) was observed under the relaxation condition, which could be practically relevant in competitive sprint swimming settings. Acute olfactory exposure to a relaxation essential oil following warm-up was associated with a small numerical reduction in sprint swimming time. Although the overall effect was not statistically significant, these exploratory findings suggest that olfactory stimulation may influence short-duration swimming performance under specific conditions and should be interpreted cautiously. Further research is warranted to confirm these effects and clarify the underlying mechanisms.