Burnout is at all-time highs across modern professions. As a typical labor-intensive industry, the high-pressure and task-driven nature of the construction industry makes construction workers more prone to burnout. It is still unclear whether increasing the professionalization level can lessen the many harmful consequences of job burnout on construction workers’ employment. Therefore, this study examined the influencing mechanism of professionalization on job burnout in the construction industry. First, a theoretical model based on the conservation of resources (COR) theory was developed with workload, job insecurity, and work–family conflict as moderating variables. A reliable sample of 441 Chinese construction workers were then recruited in the investigation. The data analysis was supported by confirmatory factor analysis (CFA) and structural equation modeling (SEM). The results indicated that: (i) an increase in the professionalization level could be directly effective in alleviating job burnout among construction workers; (ii) workload and work–family conflict could play an independent and continuous mediating role between professionalization and job burnout; and (iii) while job insecurity caused by a low professionalization did not have a direct impact on job burnout, it could have an indirect impact on job burnout through workload and work–family conflict, respectively. This study enriches the literature on job burnout among construction workers, as well as provides a theoretical basis and practical management guidance for Chinese construction companies to alleviate job burnout in workers from a professionalization standpoint.