The Asian Working Group for Sarcopenia 2019 consensus emphasized nutritional assessment and intervention for community-dwelling older people with sarcopenia status. This study aimed to examine the association of serum albumin and dietary protein intake (DPI) with all-cause mortality among older adults at risk of sarcopenia. We enrolled 1763 older adults at risk of sarcopenia in the Chinese Longitudinal Healthy Longevity Survey (2012–2018) using calf circumference and handgrip strength. Serum albumin concentrations were measured using bromocresol green methods, and DPI frequency was evaluated using a semi-quantitative questionnaire at baseline. Cox proportional hazards models were used to explore the association of serum albumin and DPI with all-cause mortality. During 5606.3 person-years of follow-up (median: 3.28 years), 802 older people died. After adjusting for socio-demographics, health behaviors, and clinical characteristics, we observed an inverse linear association between serum albumin and all-cause mortality (P_non-linear = 0.429). Participants with low albumin levels (<40.0 g/L) had a 43 % higher risk of mortality than their counterparts (hazard ratio (HR) = 1.43, 95 % confidence interval (CI) = 1.22–1.66). There was no significant association between DPI and mortality (P_s > 0.05). Moreover, the association between low albumin and all-cause mortality remained significant in the lower DPI subgroup (HR = 1.47, 95 % CI = 1.18–1.85), but was not significant in the high DPI subgroup (HR = 1.15, 95 % CI = 0.92–1.39). Serum albumin levels are inversely associated with all-cause mortality in community-based older adults at risk of sarcopenia. Sufficient dietary protein consumption may attenuate the effect of low serum albumin on increased mortality and potential mechanisms for the interaction warrant further exploration.