The use and perceptions of smartphone-based mental health applications (MH-Apps) in Saudi Arabia require exploration. This study investigated MH-App use among Saudi Arabian healthcare workers (HCWs), including psychiatrists, psychologists, and family medicine physicians. It also assessed HCWs’ interest in and willingness to integrate these apps into their practices, as well as their cognitive flexibility and its relationship with their attitudes and app use. This cross-sectional study involved 386 participants recruited using convenience and snowball sampling. The Cognitive Flexibility Scale (CFS) was used to assess cognitive flexibility. The results showed that 33.2% of HCWs downloaded MH-Apps, with 67.9% considering them somewhat beneficial. However, most had not yet tried them. Only 7% of HCWs strongly agreed that these apps are evidence-based. Concerns about using these apps in their practices were reported by 36.5% of HCWs, with the most common concern being the lack of evidence-based support. The primary reason for downloading MH-Apps for personal use was to improve mental well-being, whereas patient-related use was psychoeducation. Furthermore, 27.5% of HCWs recommended MH-Apps to their patients, with old age, women, and psychiatrists/psychologists more likely to recommend them. Higher CFS scores were more strongly associated with older HCWs, those who had ever recommended MH-Apps, and those who used the apps. Saudi Arabian HCWs should be encouraged to use and recommend MH-Apps, with more evidence-based research needed to address concerns. Further research on cognitive flexibility’s implications for clinical practice is also warranted.