Formic acid (HCOOH) can be exclusively prepared through CO 2 electroreduction at an industrial current density (0.5 A cm -2 ). However, the global annual demand for formic acid is only ∼1 million tons, far less than the current CO 2 emission scale. The exploration of an economical and green approach to upgrading CO 2 -derived formic acid is significant. Here, we report an electrochemical process to convert formic acid and nitrite into high-valued formamide over a copper catalyst under ambient conditions, which offers the selectivity from formic acid to formamide up to 90.0%. Isotope-labeled in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy and quasi in situ electron paramagnetic resonance results reveal the key C-N bond formation through coupling *CHO and *NH 2 intermediates. This work offers an electrochemical strategy to upgrade CO 2 -derived formic acid into high-value formamide.