This study examined the mediating role of person–environment (P-E) fit in the relationships of perceived social support (PSS) with perceived employability and career decision self-efficacy (CDSE). The moderating role of gender was also tested in the PSS and P-E fit relationship and in the P-E fit mediated relationships of PSS with perceived employability and CDSE. Seven hundred and ninety-nine Chinese university students returned usable questionnaires. Data were analyzed using structural equation modeling (SEM). Results demonstrated that P-E fit fully mediated the relationship between PSS and perceived employability and partially mediated the PSS–CDSE relationship. Multi-group SEM revealed that the relationship between PSS and P-E fit was stronger among males than among females. This gender difference also contributed to the gender difference in the indirect relationships of PSS with perceived employability and CDSE via P-E fit, such that these indirect relationships were stronger for males than for females.