This study adopted mixed-methods research to explore the effects of reminiscing about nostalgic smells on the physiological and psychological responses of older people in long-term care facilities. A total of 60 participants were randomly divided into two groups and each participant was either interviewed regarding their reminiscence about nostalgic smells (experimental group) or were engaged in daily conversation (control group). The results indicated that anxiety and depression symptoms were more effectively relieved in the experimental group than in the control group. Moreover, most of the nostalgic smells recalled by the experimental group were associated with naturally occurring smells. Regarding heart rate variability, the normalised low-frequency of the experimental group decreased significantly. The results verified the utility of using reminiscence about olfactory memories in reminiscence therapy as this can calm anxiety and lessen depression, which can be very important for older adults living in long-term care facilities.