Music has a well-documented capacity to influence emotional, physiological, and behavioral states, making it a powerful medium for shaping human experience. A fundamental characteristic underlying many of these effects is predictability: listeners continuously form expectations about upcoming musical events based on learned regularities in musical structure. When music confirms or violates these expectations, it can meaningfully shape the listener’s perceptual and emotional experience. Therefore, variations in melodic predictability, ranging from highly regular, familiar patterns to more unexpected or ambiguous sequences, can be expected to differentially affect listeners’ internal states. The objective of this study is to investigate the influence of melodic predictability on subjective and physiological arousal in healthy older adults. Using a within-subject experimental design, 71 older participants listened to melodies varying in melodic predictability while subjective arousal was assessed using a visual analogue scale (VAS), alongside continuous psychophysiological measures of electrodermal activity (EDA) and heart rate (HR). Linear mixed model analyses indicated small but significant effects on subjective arousal ratings and on EDA, indicating psychological and sympathetic effects of melodic predictability. HR results, however, showed small but not significant effects. These findings help us understand melodic predictability as a characteristic of music in influencing arousal in older adults, which may inform the field of music therapy for clinical populations including older adults with dementia. Further research is needed to explore how musical predictability contributes to arousal regulation as a mechanism for supporting older adults with dementia.