Research suggests that online interventions preventing risky substance use can improve student health. There is an increasing interest in transferring evidence-based online programs into university health promotion practice. However, little is known about how to best tailor the implementation process to capacities and context of individual universities. The purpose of this study was to assess the level of readiness (capacity) of German universities concerning the implementation of evidence-based online programs for risky substance use prevention employing an adapted Community Readiness Assessment (CRA) and to develop tailored action plans for implementation. The CRA involved 43 semi-structured interviews with key persons at 10 German universities. The interviews addressed five dimensions (knowledge of efforts, leadership, community climate, knowledge of the issue, and resources) at nine possible readiness stages (no awareness—ownership) and additional contextual factors. Overall, readiness for implementing online interventions across universities was rather low. Universities readiness levels ranged between the denial stage with a score of 2.1 and the preplanning stage with a score of 4.4. University-specific readiness was very heterogeneous. On the basis of the results of the CRA, universities received feedback and options for training on how to take the necessary steps to increase readiness and to prepare program implementation. The adapted version of the CRA was well suited to inform future implementation of evidence-based online programs for the prevention of risky substance use at participating universities.