Uncontrollable lithium (Li) dendrite growth has hampered the application of lithium metal batteries (LMBs). Herein, a novel plastic crystal composite polymer electrolyte (nh-CPE) consisting of multifunctional two-dimensional (2D) molybdenum disulfide (MoS2) and ion-conducting one-dimensional (1D) surfactant oxidized cellulose nanocrystal (OCNC) is developed to overcome this challenge. The nh-CPE possesses good Li-dendrite-suppressing ability, which is attributed to the well-designed three-dimensional (3D) ion conducting network constructed by homogeneously dispersed MoS2 and OCNC. This structure facilitates Li-ion conductivity and enables uniform Li deposition on the anode. Moreover, the impermeable MoS2 nano-flakes with excellent mechanical strength serve as physical barriers to hold the electrolyte-electrode interface stability and consequently block Li dendrite growth and enhance fire retardancy. When applied in LMB, the nh-CPE exhibits excellent cycle performance and rate capability, with 90% capacity retention after 200 cycles at 0.5 C and 60 °C, and a discharge capacity of 128 mAh g−1 at 1 C. Notably, owing to high room-temperature ionic conductivity (0.8 mS cm−1), the cell with nh-CPE cycled at room temperature delivers an initial discharge capacity of 144 mAh g−1. The outstanding performance and simple process offer great opportunity to promote Li-dendrite-suppressing LMBs for practical application.