In recent years, the use of precast concrete systems has increased due to their high construction speed, improved quality control, and cost reduction. Flexural beam–column connections in precast concrete structures can be constructed using wet or dry methods; however, their flexural rigidity and seismic performance have received limited attention, particularly in seismic regions. Considering the high seismicity of Iran, reducing the effective seismic weight of structures while maintaining sufficient concrete strength is of great importance. In this context, structural lightweight concrete can reduce seismic mass and facilitate the transportation and construction of precast members. In this study, three exterior flexural beam–column connection specimens were tested under cyclic loading. These included a cast-in-place normal-weight concrete connection, a cast-in-place lightweight concrete connection, and a precast connection combining normal-weight and lightweight concrete. The failure mechanisms, load capacity, initial stiffness, and energy dissipation of the specimens were evaluated and compared. Finite element modeling was also performed to simulate the behavior of the precast lightweight concrete connection. The results showed that the energy dissipation of the precast connection was 19% and 33% higher than those of the cast-in-place normal-weight and lightweight concrete connections, respectively. In addition, the ultimate load of the precast connection increased by 12% and 20% compared to the corresponding cast-in-place connections. These results indicate improved seismic performance of the precast lightweight concrete connection.