This paper investigated the relationship between corporate governance mechanisms and firm performance in Vietnam. Based on a dataset of 101 HOSE-listed manufacturing firms, the results showed that CEOs’ knowledge capability, gender diversity, and board size are positively associated with firm performance, whereas firm age is negatively associated. These findings suggested that firms should consider enlarging the boardrooms, but to a certain extent to avoid an inverse-U-shaped decline of performance; furthermore, firms should promote women executives’ presence in a boardroom for it brings greater cultural-diversity benefits and inhibits information asymmetry. Contrary, the aging process impedes firms’ growth. It depreciates their values in terms of total assets, so managers must review their assets’ net value after each working year to avoid such a hardship. However, the thesis constrains itself since it did not treat the TMTs’ knowledge capability equally as the CEOs’ and completely excluded their treatment. Besides, it did not regard the effect of external governance mechanisms such as the supply-demand relationship, customer behavior, market imperfections, and market concentration due to data unavailability. Based on the main findings, several suggestions are set forth for firms and managers to enhance performance and minimize a poor governance mechanism’s adverse consequence.