Background and aim: A body of evidence is supporting the association between (the risk of) malnutrition in relation to physical performance, muscle strength, risk for depression and cognitive status in geriatric outpatients. Associations between being malnourished according to the newly proposed ESPEN definition for malnutrition and clinically relevant outcome measures of the aforementioned variables have not been confirmed yet. Therefore, the aim of this study was to examine the association between being malnourished according to the ESPEN definition and clinically relevant outcome measures in geriatric outpatients. Methods: Associations between malnutrition and handgrip strength (HGS, kg), short physical performance battery (SPPB-score, points), timed up and go test (TUG, seconds), and hospital anxiety and depression scale (HADS depression score, points), were analysed using linear regression. History of falls (falls, yes/no) and a low score on the Mini Mental-State Examination (MMSE-score ≤ 24 points) were analysed using logistic regression. All analyses were adjusted for age and gender. Results: A total of 185 geriatric outpatients (60% women) were included. The mean age was 82 (± 7.3) years. Being malnourished (8.2%) according to the ESPEN definition was significantly associated with a lower HGS (− 3.38 kg, p = 0.031), lower SPPB score (− 1.8 point, p = 0.025), higher TUG time (1.35 times higher time, p = 0.020) and higher HADS depression score (2.03 times higher score, p = 0.007). Being malnourished tended towards an association with falls (OR 3.84, p = 0.087). No significant association was found with low MMSE score (OR 2.61, p = 0.110). Conclusion: This study is the first to confirm the association between being malnourished, defined by the ESPEN definition and clinically relevant outcome measures in geriatric outpatients.