This study aimed to detect the functional and emotional impact of COVID-19 lockdown on institutionalized older adults with sarcopenia during a 15-month follow-up. A prospective longitudinal cohort study was conducted in a nursing home. Participants were screened for sarcopenia, and those with a score of ≥4 points according to SARC-F questionnaire were included. Assessments were performed pre-lockdown (T1), 12 months (T2) after, and at a 15-month follow-up (T3). Functional measurements included chair stand test, handgrip, biceps brachii and quadriceps femoris strengths, appendicular skeletal mass, gait speed, Short Physical Performance Battery, and Timed Up-and-Go test. Emotional assessments included Short-Form Health Survey, Geriatric Depression Scale-Short Form, and the Mini-Mental State Examination. The analyzed sample showed a reduction in bicep strength, and other upper and lower limb strength variables showed a decreasing trend with no changes regarding muscle mass. Physical performance showed a change, specifically a deterioration in the subtest related to balance. Cognitive and emotional components were affected and quality of life was decreased. It is of paramount importance to focus on sarcopenic older adults since their characteristics can deteriorate when isolation measures are conducted