Objective: This systematic review aims to evaluate the effectiveness of Basic Life Support (BLS) training programs delivered by adults to lay populations, with a focus on their impact on knowledge retention, practical skill performance, and confidence in emergency situations. Methods: We conducted a comprehensive systematic review following the PICOTT framework. Searches were executed across several databases, including PubMed, Cochrane Library, Embase, and CINAHL. Studies were included if they involved BLS training provided by adults to laypersons and employed randomized controlled trials, non-randomized trials, or observational study designs. Exclusion criteria encompassed studies focused on healthcare professionals or non-BLS training interventions. Results: From an initial pool of 270 studies, 40 met the predefined inclusion criteria. The review found that adult-led BLS training significantly enhances laypersons' knowledge retention, skill performance, and confidence. Specifically, training led to a marked improvement in participants' ability to recall and apply BLS techniques, perform necessary skills accurately, and feel more assured in their capability to respond to emergencies. The effectiveness of training was evident immediately post-intervention, with evidence supporting the necessity of refresher courses and ongoing practice to maintain skills over time. Conclusion: Adult-led BLS training is highly effective in improving emergency response skills among laypersons. To sustain these benefits, it is crucial to employ a variety of training methods and implement regular follow-up sessions. Such strategies are essential for ensuring long-term retention of BLS skills and enhancing overall emergency preparedness.