Purpose: Supporting the provision of intensive care medicine through telehealth potentially improves process quality. This may improve patient recovery and long-term outcomes. We investigated the effectiveness of a multifaceted telemedical programme on the adherence to German quality indicators (QIs) in a regional network of intensive care units (ICUs) in Germany. Methods: We conducted an investigator-initiated, large-scale, open-label, stepped-wedge cluster randomised controlled trial enrolling adult ICU patients with an expected ICU stay of ≥ 24 h. Twelve ICU clusters in Berlin and Brandenburg were randomly assigned to three sequence groups to transition from control (standard care) to the intervention condition (telemedicine). The quality improvement intervention consisted of daily telemedical rounds guided by eight German acute ICU care QIs and expert consultations. Co-primary effectiveness outcomes were patient-specific daily adherence (fulfilled yes/no) to QIs, assessed by a central end point adjudication committee. Analyses used mixed-effects logistic modelling adjusted for time. This study is completed and registered with ClinicalTrials.gov (NCT03671447). Results: Between September 4, 2018, and March 31, 2020, 1463 patients (414 treated on control, 1049 on intervention condition) were enrolled at ten clusters, resulting in 14,783 evaluated days. Two randomised clusters recruited no patients (one withdrew informed consent; one dropped out). The intervention, as implemented, significantly increased QI performance for “sedation, analgesia and delirium” (adjusted odds ratio (99.375% confidence interval [CI]) 5.328, 3.395-8.358), “ventilation” (OR 2.248, 1.198-4.217), “weaning from ventilation” (OR 9.049, 2.707-30.247), “infection management” (OR 4.397, 1.482-13.037), “enteral nutrition” (OR 1.579, 1.032-2.416), “patient and family communication” (OR 6.787, 3.976-11.589), and "early mobilisation" (OR 3.161, 2.160-4.624). No evidence for a difference in adherence to “daily multi-professional and interdisciplinary clinical visits” between both conditions was found (OR 1.606, 0.780–3.309). Temporal trends related and unrelated to the intervention were detected. 149 patients died during their index ICU stay (45 treated on control, 104 on intervention condition). Conclusion: A telemedical quality improvement program increased adherence to seven evidence-based German performance indicators in acute ICU care. These results need further confirmation in a broader setting of regional, non-academic community hospitals and other healthcare systems.