Background: This study explored how simulation-based education in undergraduate nursing programs influenced the clinical transition of early-stage nurses. It examined how simulation experiences facilitated the application of knowledge, skills, and attitudes in clinical settings. Methods: A qualitative descriptive study was conducted through two focus group interviews with 12 early-stage nurses with less than three years of clinical experience who had completed simulation-based education during their undergraduate programs. Participants were selected using purposive sampling, and data were collected between December 14 and 20, 2024. Data were analyzed using qualitative content analysis. Results: Four superordinate categories, eight categories, and 21 subcategories were identified, establishing a foundation for clinical application through simulation-based learning, facilitation of clinical application, adaptation to clinical practice and professional roles, long-term effects, and advanced competency development. Simulation-based education enhanced clinical reasoning and decision-making, self-directed learning, communication, and patient-centered care, while reducing anxiety and strengthening professional identity. The participants also highlighted the need for scenario diversity, high fidelity, and sufficient time for feedback and preparation to optimize the simulation learning environments. Conclusions: Simulation-based education positively influenced the clinical transition of early-stage nurses by bridging academic learning with practice. To maximize their effectiveness, simulations should be introduced earlier, implemented more systematically, and aligned better with real clinical settings.