ABSTRACT Background The Cancer Behavior Inventory Brief Form (CBI‐B) allows assessing self‐efficacy for coping with cancer as a personal resource of patients facing a diagnosis of cancer and its treatment. While psychometric analyses of CBI‐B versions in other languages than English exist, the German version has not been analyzed more thoroughly in this respect yet. Aims Against this background, we analyzed the factor structure, internal consistency, and criterion validity of the German 12‐item version of the Cancer Behavior Inventory Brief Form, the CBI‐B‐D‐12. Methods Based on a pooled sample of N = 1034 cancer patients from various settings, we performed confirmative factor analyses, computed Cronbach's α and McDonald's ω for the 12‐item summary scale, and determined criterion correlations with measures of patients' health‐related quality of life, anxiety, depression, fear of progression, and fatigue. Results With few adjustments, confirmative factor analysis revealed good fit of a 4‐factor model identifying the same dimensions of coping self‐efficacy as the original instrument ( Maintaining Independence and Positive Attitude , Participating in Medical Care , Coping and Stress Management , and Managing Affect ). With values of Cronbach's α and McDonald's ω being 0.89 and 0.88 respectively, estimates of the scale's internal consistency were good, and criterion correlations further supported its validity. Conclusions The German 12‐item version of the CBI‐B represents a reliable measure of cancer patients' self‐efficacy for coping with cancer that is valid in terms of factorial structure and correlations with major distress and quality of life criteria. It may thus be used in clinical practice and psycho‐oncological research.