The transition of nurses into high-acuity cardiovascular care settings presents critical challenges in patient safety, skill acquisition, and clinical autonomy. This contribution describes the development and preliminary outcomes of a structured, simulation-supported onboarding program implemented in a high-volume cardiovascular center in Italy. The initiative aimed to accelerate professional adaptation of newly hired nurses transitioning into anesthesiology, intensive care, and operating room environments. Medium-fidelity simulation sessions were embedded throughout a three-month on-the-job training pathway to enhance preparedness for both routine and high-risk clinical scenarios, including pediatric and maternal-infant cardiac care. Clinical tutors guided participants through progressive responsibilities, with structured assessments and debriefings tracking performance. Early results from six participants indicate improved safe clinical integration, and increased confidence, with three nurses completing the program and achieving autonomy in less than the expected timeframe. While certain technical areas—such as pharmacological protocols and blood product management—remained challenging, no major safety issues were reported. These findings suggest that simulation-based onboarding may effectively reduce integration time while maintaining quality and safety standards. Future directions include scaling the model to other units, establish structured outcome monitoring, enhancing cross-disciplinary simulation, and integrating virtual training components.