Background <p>Despite guideline recommendations, physical activity implementation remains limited in hospitalized older adults. This study aimed to assess physical activity levels, exercise awareness, and associations with geriatric syndromes in this population.</p> Methods <p>We conducted a cross-sectional study among hospitalized older adults (≥ 60 years). Pre-hospitalization physical activity was assessed using the International Physical Activity Questionnaire, and categorized as low, moderate, or high according to standard criteria. In-hospital physical activity was objectively quantified via pedometer-measured daily walking steps. A subsample (<i>n</i> = 137) completed a structured questionnaire on exercise awareness. Seven geriatric syndromes, including sarcopenia, frailty, malnutrition, depression, anxiety, sleep disorder, and pain, were evaluated. Multivariable ordinal and linear regression models were used to examine associations between geriatric syndromes and physical activity.</p> Results <p>Among 446 included participants (mean age 73.2 ± 8.5 years, 59.2% male), 58.3% did not meet guideline-recommended exercise volumes prior to hospitalization. In-hospital daily walking steps count was relatively low (median: 1467, IQR: 432–3292). Over 80% of a subsample were unaware of recommended exercise volumes and types. After adjustment, sarcopenia (OR = 0.35, 95% CI: 0.23–0.55), frailty (OR = 0.18, 95% CI: 0.10–0.33), malnutrition (OR = 0.30, 95% CI: 0.20–0.44), and depression (OR = 0.37, 95% CI: 0.19–0.72) were significantly associated with lower pre-hospitalization physical activity levels. These conditions were also associated with fewer daily in-hospital walking steps: sarcopenia (β = -1730, 95% CI: -2330 to -1140), frailty (β = -2780, 95% CI: -3630 to -1920), malnutrition (β = -1400, 95% CI: -1930 to -869), and depression (β = -1170, 95% CI: -1890 to -442 steps/day). No significant associations were observed for anxiety, pain, or sleep disorders. A graded association was observed between higher geriatric syndrome burden and lower physical activity levels, both before and during hospitalization.</p> Conclusions <p>Hospitalized older adults in this study exhibited low physical activity levels and poor awareness of exercise guidelines. Geriatric syndromes, particularly sarcopenia, frailty, malnutrition, and depression, were strongly associated with reduced physical activity. These findings highlight the need for further research into integrated, syndrome-targeted strategies combined with exercise education to promote physical activity in this population.</p> Trial registration <p>Not applicable. Clinical trial number: not applicable.</p>