Within urban green systems, forest spatial structure shapes how individuals perceive environments and experience psychophysiological responses. Although forest structure has been examined from ecological and aesthetic perspectives, age-related differences in perceptual and regulatory responses across forest spatial typologies remain insufficiently understood. To address this gap, this study developed an integrated multimodal analytical framework that combines immersive virtual reality, eye tracking, physiological sensing, and affective assessment to examine age-sensitive health-related responses to forest spatial typologies. Three forest spatial typologies were investigated: open, semi-open, and enclosed. Panoramic scenes were standardized for visual authenticity and quantified to support typology classification. During virtual reality exposure, eye-tracking indicators capturing attention allocation were synchronized with physiological measures and affect ratings, enabling comparisons between 30 young and 25 elderly participants, with a total sample of 55 participants. Results revealed marked age-by-spatial-typology interaction effects in eye-tracking indicators and perceptual–affective responses, whereas autonomic physiological indicators remained stable. Elderly participants demonstrated the highest visual satisfaction in open forest structures. In contrast, young participants exhibited shorter time to first fixation in enclosed typology and higher visit counts in semi-open typology, reflecting attention allocation patterns across spatial configurations. Subjectively, elderly participants reported a Positive Affect score of 38.64, 44.7% higher than that of young participants. Objectively, the mean pupil diameter of young participants reached 3.37, representing a 27.2% increase relative to that of elderly participants. These findings show that forest spatial typology shapes age-sensitive multimodal responses, including visual attention, psychophysiological regulation, and affect, and inform inclusive, resilience-oriented urban green-space planning under ongoing demographic transition pressures.