Carbon dioxide reduction reaction (CO2RR) is a promising technology for mitigating greenhouse gas emission and achieving carbon neutrality. However, coupling CO2RR with other reactions to produce high value-added chemicals remains a challenge. In this work, we report self-assembled nanofibers composed of ultra-thin AuCu alloy nanowires possessing a Boerdijk-Coxeter structure with (111)-dominant facets for the electrosynthesis of urea by coupling CO2RR with nitrite reduction reaction (NO2−RR). The rich structural defects and AuCu bimetallic alloy composition provide a large number of highly catalytically active sites. The constructed AuCu nanofibers display excellent urea synthesis performance in the electrolyte solution containing 0.01 M KNO2 with continuous drumming of CO2, achieving a high urea yield rate of up to 3889.6 µg h− 1 mg− 1cat. and a high Faraday efficiency of 24.7% at -0.9 V. This work provides a feasible method for the rational design of self-assembled bimetallic nanofibers for electrosynthesis of urea under ambient conditions.