In this study, an innovative split precast assembly technique for bridge cap beams is proposed, and its structural performance is investigated via experimental testing and finite element analysis. A scaled (1:3.6) sample was tested to evaluate the flexural behavior, crack resistance, and ultimate capacity of the split precast cap beam. The results indicate that the proposed technique achieves moderately reinforced flexural failure at cantilever roots with satisfactory ductility, with average crack resistance and safety reserve coefficients of 1.15 and 1.74, respectively. Strain analysis confirmed effective composite action between the precast components and the postcast strip, validating the space plane-section assumption. The experiment reveals localized stress concentrations at the beam ends and cantilever roots that require special reinforcement detailing. A nonlinear finite element model was developed and validated against test data, which showed good agreement and successfully captured behavior, including crack initiation and failure modes. The split precast technique has been successfully implemented in approximately 40 cap beams for the Outer Ring East Section traffic improvement project in Shanghai, China. The findings provide both theoretical and practical foundations for optimizing and promoting this efficient construction method in bridge engineering applications.