Background: Effective education in basic life support (BLS) may improve the early initiation of high-quality cardiopulmonary resuscitation and automated external defibrillation (CPR-AED). Aim: To compare the learning outcome in terms of practical skills and knowledge of BLS after participating in learning activities related to BLS, with and without web-based education in cardiovascular diseases (CVD). Methods: Laymen (n = 2,623) were cluster randomised to either BLS education or to web-based education in CVD before BLS training. The participants were assessed by a questionnaire for theoretical knowledge and then by a simulated scenario for practical skills. The total score for practical skills in BLS six months after training was the primary outcome. The total score for practical skills directly after training, separate variables and self-assessed knowledge, confidence and willingness, directly and six months after training, were the secondary outcomes. Results: BLS with web-based education was more effective than BLS without web-based education and obtained a statistically significant higher total score for practical skills at six months (mean 58.8, SD 5.0 vs mean 58.0, SD 5.0; p = 0.03) and directly after training (mean 59.6, SD 4.8 vs mean 58.7, SD 4.9; p = 0.004). Conclusion: A web-based education in CVD in addition to BLS training enhanced the learning outcome with a statistically significant higher total score for performed practical skills in BLS as compared to BLS training alone. However, in terms of the outcomes, the differences were minor, and the clinical relevance of our findings has a limited practical impact.