Wide bandgap semiconductors are ideal materials for ultraviolet (UV) photodetectors (PDs) due to their high-efficiency UV light absorption and stable opto-electronic properties. This review summarizes recent advancements in both traditional and emerging wide bandgap-based UV PDs, highlighting their roles in UV imaging, communication, and alarming. It examines methods to enhance UV PD performance, discussing advantages, challenges, and future research prospects. The review aims to spark innovation and guide future development and application of UV PDs. UV PDs are categorized into vacuum and solid-state devices. Solid-state PDs, primarily using wide bandgap semiconductors, offer advantages such as small size, light weight, and excellent UV response ability. Examples include photoconductive and photovoltaic PDs. Wide bandgap semiconductors like GaN, SiC, and diamond-based PDs are commercially available, while new materials such as metal oxides and 2D materials are being explored for flexible and wearable PDs. To improve UV PD performance, various approaches are employed, including surface plasmon resonance, nanostructure design, surface/interface carrier transport modulation, and the ferro/pyro/piezo-phototronic effect. These methods enhance UV PD performance through tailored strategies. Surface plasmon resonance, for example, enhances photocurrent by injecting hot electrons into the semiconductor. Nanostructure design, such as SnO₂/ZnO heterostructures, reduces dark current and improves on/off ratios. The ferro/pyro/piezo-phototronic effect enhances charge carrier transport and photocurrent by modifying interfacial band structures and charge transfer properties. UV PDs have diverse applications, including imaging, communication, and alarming. In imaging, UV PDs can penetrate smoke, fog, and clouds, enabling observation under their cover. They are used in atmospheric, geophysical, and biomedical studies. In communication, UV PDs offer advantages such as reduced loss, increased capacity, and minimized interference. They are used in point-to-point, multipoint, and reflective communication modes. In alarming, UV PDs monitor UV radiation intensity and exposure time, triggering alarms for protective measures. They are also used in fire detection due to the strong UV emission during combustion. UV PDs are also applied in high-voltage leakage detection and fire early warning. They serve as effective flame detectors due to the strong UV light emitted during combustion. These PDs are installed in fire-prone areas and trigger alarms upon detecting flames. This review highlights the potential of wide bandgap semiconductors in UV PDs and their diverse applications. It provides a comprehensive overview of ongoing research and future directions, aiming to advance UV PD technology.Wide bandgap semiconductors are ideal materials for ultraviolet (UV) photodetectors (PDs) due to their high-efficiency UV light absorption and stable opto-electronic properties. This review summarizes recent advancements in both traditional and emerging wide bandgap-based UV PDs, highlighting their roles in UV imaging, communication, and alarming. It examines methods to enhance UV PD performance, discussing advantages, challenges, and future research prospects. The review aims to spark innovation and guide future development and application of UV PDs. UV PDs are categorized into vacuum and solid-state devices. Solid-state PDs, primarily using wide bandgap semiconductors, offer advantages such as small size, light weight, and excellent UV response ability. Examples include photoconductive and photovoltaic PDs. Wide bandgap semiconductors like GaN, SiC, and diamond-based PDs are commercially available, while new materials such as metal oxides and 2D materials are being explored for flexible and wearable PDs. To improve UV PD performance, various approaches are employed, including surface plasmon resonance, nanostructure design, surface/interface carrier transport modulation, and the ferro/pyro/piezo-phototronic effect. These methods enhance UV PD performance through tailored strategies. Surface plasmon resonance, for example, enhances photocurrent by injecting hot electrons into the semiconductor. Nanostructure design, such as SnO₂/ZnO heterostructures, reduces dark current and improves on/off ratios. The ferro/pyro/piezo-phototronic effect enhances charge carrier transport and photocurrent by modifying interfacial band structures and charge transfer properties. UV PDs have diverse applications, including imaging, communication, and alarming. In imaging, UV PDs can penetrate smoke, fog, and clouds, enabling observation under their cover. They are used in atmospheric, geophysical, and biomedical studies. In communication, UV PDs offer advantages such as reduced loss, increased capacity, and minimized interference. They are used in point-to-point, multipoint, and reflective communication modes. In alarming, UV PDs monitor UV radiation intensity and exposure time, triggering alarms for protective measures. They are also used in fire detection due to the strong UV emission during combustion. UV PDs are also applied in high-voltage leakage detection and fire early warning. They serve as effective flame detectors due to the strong UV light emitted during combustion. These PDs are installed in fire-prone areas and trigger alarms upon detecting flames. This review highlights the potential of wide bandgap semiconductors in UV PDs and their diverse applications. It provides a comprehensive overview of ongoing research and future directions, aiming to advance UV PD technology.