Combat sports athletes (CSAs) operate in high-stress environments where exceptional physical conditioning must be complemented by strong psychological resilience. This mini-review examines the critical role of mental toughness (MT) in combat sports, highlighting its key components and influence on athletic performance. Despite the universally high training loads reported by CSAs, the distinguishing factor between regular and exceptional athletes often lies in their mental toughness. The demanding training and nutrition regimens required for weight class compliance frequently compel CSAs to drastically reduce food and fluid intake, sometimes leading to extreme measures such as gut manipulation techniques or doping. This challenging environment necessitates a mindset capable of withstanding significant pressure, particularly for younger athletes navigating puberty and external expectations from coaches and peers. Developing mental toughness emerges as a vital component for success in combat sports, as it can alleviate performance anxiety and mitigate psychological stressors inherent in competitive settings. Evidence indicates that psychological skills training can enhance self-reported MT, with sport-specific techniques—such as imagery, relaxation strategies, and cognitive interruption—effectively fostering core attributes like hardiness, self-esteem, self-efficacy, dispositional optimism, and positive affectivity. Furthermore, perceptions of stress among CSAs vary; while some view intense training as a testament to dedication, others may find it overwhelming. This distinction emphasizes the importance of mindset, motivation, and individual resilience in shaping athletic performance outcomes. The findings underscore the necessity of integrating mental toughness training into the preparation of combat sports athletes.