Although research examining the association between problematic smartphone use and mental health has grown recently, there is a lack of studies investigating possible associations with physical (somatic) symptoms. Moreover, many studies are based on student samples from North America and China, limiting their generalizability. The current study aimed to examine problematic smartphone use in a broad sample of German adults. An online survey comprising demographic questions, problematic smartphone use scales and somatic symptom inventories, as well as depression, anxiety, stress, and sleep quality scales was completed by 930 participants. Problematic smartphone users reported longer usage per day, more interruptions to activities to check their smartphones, and higher scores for stress, depression, anxiety, sleep disturbances, and somatic symptoms than did unproblematic users. In comparison, both groups allocated similar proportions of time to various applications. The results showed small to moderate bivariate associations between problematic smartphone use and indicators of mental health and somatic symptoms, while a multivariate analysis highlighted the importance of perceived stress. Since mental health and somatic symptoms are associated with problematic smartphone use, future studies should investigate the causal direction of the associations found.