Objective: To analyze the correlation between perceived stress, job burnout, and subjective well-being among undergraduate nursing interns. Methods: A total of 260 clinical nursing interns who interned in tertiary hospitals from July 2024 to April 2025 were selected as the survey subjects. They were administered the Chinese version of the Perceived Stress Scale (CPSS), the Maslach Burnout Inventory-Human Services Survey (MBI-HSS), and the General Well-being Schedule (GWB) to evaluate the correlation between perceived stress, job burnout, and subjective well-being. Results: The subjective well-being scores of those with higher perceived stress were lower than those with moderate stress; individuals with severe job burnout had lower subjective well-being compared to those without job burnout or with mild to moderate job burnout levels (p < 0.05). Correlation analysis revealed that the subjective well-being of undergraduate nursing interns was negatively correlated with perceived stress and job burnout (p < 0.05). Conclusion: Undergraduate nursing interns experience significant perceived stress and a strong sense of job burnout. Their subjective well-being is correlated with their perceived stress and job burnout. It is necessary to optimize the clinical teaching model and provide psychological skills training to alleviate the interns’ perceived stress and job burnout, thereby significantly enhancing their subjective well-being.