Retronasal odor perception interacts with taste and other sensory modalities during flavor perception. However, the influence of sweet taste on retronasal odor identification, and its modulation by age, remains poorly understood. Here, we investigated the effects of gymnemic acid (GA)-induced sweet taste suppression on retronasal odor identification in younger (n = 83) and older adults (n = 41). Using a mixed factorial design, participants completed the ThreeT test under normal and sweet taste suppression conditions, with subjective taste ratings, odor identification accuracy, and reaction times recorded. Results showed that oral rinsing with GA significantly reduced perceived sweetness intensity, confirming effective sweet taste suppression. At the behavioral level, sweet taste suppression affected retronasal odor identification in an age-dependent manner, as indicated by a significant age group × condition interaction. Follow-up analyses indicated that odor identification performance decreased in older adults under sweet taste suppression (p = 0.003), whereas no significant change was observed in younger adults (p = 0.330). Reaction times showed a similar reduction under sweet taste suppression across age groups. These findings suggest that the contribution of sweet taste to retronasal odor identification is age-dependent, with older adults showing greater reliance on gustatory input for successful odor identification. The results provide new insights into gustatory–olfactory interactions and highlight the importance of multisensory integration mechanisms in chemosensory aging, with potential implications for understanding flavor perception under reduced-sugar conditions across the lifespan.