Although mobile devices support physicians in a variety of ways in everyday clinical practice, the use of (personal) mobile devices poses potential risks for information security, data protection, and patient safety in hospitals. We used a cross-sectional survey-based study design to assess the current state of smartphone use among resident physicians in hospitals and to investigate the relationships between working conditions, current smartphone usage patterns, and security-related behavior. In total, data from 343 participating physicians could be analyzed. A large majority (98.3%) used their smartphones during clinical practice. Of the respondents who used a smartphone during clinical practice, only 4.5% were provided with a smartphone by their employer. Approximately three-quarters of the respondents who used their smartphones for professional communication never/almost never used dedicated GDPR-compliant messenger services. Using a hierarchical regression model, we found a significant effect of the organizational resources Social Support (Supervisor) and Information Security-related Communication on security-related behavior during the selection of medical apps (App Selection). Smartphones are an important part of digital support for physicians in everyday clinical practice. To minimize the risks of use, technical and organizational measures should be taken by the hospital management, resulting, for example, in a Bring-Your-Own-Device (BYOD) initiative.