The design of highly active and cost-effective photoelectrocatalysts for effective hydrogen generation becomes a mandatory issue due to the demands on sustainable solar fuels. Herein a novel ternary Co–Cd–Fe LDH/PbI2 nanocomposite (T-LDH/PbI2NC) was fabricated by combining strategies of doping and in-situ loading of ternary Co–Cd–Fe LDH. The morphological, structural, and optical properties of PbI2, T-LDH, and T-LDH/PbI2 NC were studied by different techniques. LDH narrows the bandgap of the nanocomposite to 2.53 eV which prolongs the lifetime of the photo-induced electrons. Subsequently, the use of T-LDH/PbI2 NC improves the photoelectrocatalytic (PEC) H2 production rate. T-LDH/PbI2 NC shows a catalytic H2 production rate of 107.53 mmol h−1 cm−2 with IPCE% of 83.8% for 307 nm and 67.3% for 508 nm. The ABPE% reaches its supreme of 4.24% for − 0.58 V and 5.41% for − 0.97 V, these values are the highest values yet for LDH-based photocatalysts. The influences of the operating temperature and monochromatic illumination on the PEC performance were studied. Also, the electrochemical surface area, thermodynamic parameters, and Tafe slopes are calculated to label the hydrogen evolution mechanism. Moreover, the stability and reusability of the T-LDH/PbI2 NC photoelectrode were investigated. This work not only illustrated a simplistic and accessible way to produce a new category of highly efficient photocatalysts compared to the previously reported LDH-based PEC catalysts but also demonstrates a new point of view for improving PEC performance towards industrial water splitting under sunlight irradiation.