Lead ion (Pb2+) contamination poses a serious threat to both environmental and human health due to its high toxicity, even at trace levels. Consequently, the demand for ultrasensitive, selective, and practical detection methods has become increasingly critical for effective monitoring and remediation efforts. Among the available techniques, fluorescent chemosensors stand out for their rapid, sensitive, and often visible responses to Pb2+, enabling on-site and real-time detection. The organic small molecular fluorescent probes offer significant advantages for sensing applications, including structural tunability, ease of functionalization, large Stokes shift, photostable, tunable optical properties, high sensitivity and selectivity. This review presents a comprehensive overview of recent developments (2020–2025) in organic fluorescent and colorimetric chemosensors for Pb2+ detection, emphasizing both chemical innovations and practical applications. This review systematically explores various modern chemosensor materials such as rhodamine, triazole, peptide-based derivatives, and a wide range of Schiff-base compounds including imines, azines, and azo derivatives. It also highlights the emerging role of metal-organic frameworks (MOFs), covalent organic frameworks (COFs), and hybrid architectures in enhancing sensitivity and selectivity toward lead ions. In addition, this review delves into the fundamental principles of fluorescence-based Pb2+ sensing, outlining key design strategies, the influence of functional groups, sensing mechanisms and potential real-world applications. This work aims to serve as a valuable guide for researchers developing next-generation organic fluorescent probes for efficient and selective lead ion detection.