Amid the rapid development of higher education in China and the increasingly fierce competition among colleges, improving teachers' job satisfaction has become a critical criterion for ensuring the sustainable development of newly established undergraduate institutions and meeting the growing demand for talent cultivation. In this study I explores the impact of professional identity and work engagement on job satisfaction among teachers of different genders and ages. Based on conservation of resources theory, I utilized multiple regression analysis to investigate 637 university teachers from five newly established undergraduate institutions in Hebei Province, China. The results indicate significant differences in professional identity, job satisfaction, and work engagement among teachers of different genders and ages, with female teachers scoring higher than male teachers, and older teachers scoring higher than younger teachers. Professional identity has a significantly positive effect on job satisfaction and work engagement. Additionally, work engagement plays a partial mediating role between professional identity and job satisfaction among teachers at newly established undergraduate institutions.