Habits are highly automated behaviors that have received renewed attention in addiction research. The Self-Report Habit Index (SRHI) is a widely used measure of habits. Two cross-sectional online studies aimed at validating a German version of the SRHI to assess two everyday health-risk behaviors: caffeine consumption and smartphone/tablet use. In both studies (N = 1310), the SRHI scales (one adapted for caffeine consumption, one for smartphone/tablet use), as well as corresponding addiction scales and health outcomes (study 1), or established validity measures (study 2), were assessed. Both SRHI scales showed satisfying item characteristics, high internal consistencies (αs > .90), adequate construct validity, and a three-factorial solution with a satisfying model fit (CFI/TLIs > .95, SRMRs ≤ 0.05). Highest correlations emerged between SRHI and addiction scales. The studies show that the German SRHI can be used to validly assess health-risk behaviors. The observed strong correlations of the SRHI scales with addiction scales suggest that (self-reported) habit is indeed an important aspect to consider in addiction research.