Synthesis of urea through electrocatalytic coupling reaction of CO2 with nitrite (NO2-) represents a sustainable means to substitute the conventional energy-intensive urea synthetic protocol. The direct conversion of dilute NO2- in real wastewaters to urea with high efficiency is still a significant challenge, as C-intermediates tend to go through an extensive reduction achieving mostly C-containing productions due to the lack of N-intermediates, originating from slow diffusion rate of NO2-. Herein, we report the charge-polarized Feδ--Cuδ+ dual sites in metal/carbon heterojunction material (Cu@Fe-N-C) for co-reduction of CO2 and dilute NO2- solution (100 ppm NO2--N). The electron-rich single Fe atoms dispersed N-doped carbon (Fe-N-C) restrain *CO desorption, and the electron-deficient Cu nanoparticles (Cu) promote the deep reduction of NO2- to *NH2. As a result, the obtained Cu@Fe-N-C exhibits a high Faradic efficiency for urea of 50.05% with a yield of 850.57 mg h-1 g-1 at -0.35 V (vs. RHE) in a flow cell. Moreover, Curea-selectivity reaches to 100% and a near-unity selectivity for the value-added urea and NH3 is realized. The present results provide a valuable reference for the design of new catalysts for efficient synthesis of C-N compounds in dilute NO2- solution.