Single‐atom catalysts (SACs) have received widespread interest for their high atomic efficiency, enriched active sites, excellent catalytic performance, and low cost. However, the agglomeration of single metal atoms and the use of inactive additives for affixing powdery SACs on planar electrodes may reduce the density of active sites, diminish the charge transport to active sites, and thus suppress their performance. Herein, a series of metal–nitrogen–carbon single‐atom aerogels (M‐SAAs, M: Cu, Ni, Au, Ru) are synthesized via a universal strategy, in which the merits of metal organic frameworks and carbon aerogels are perfectly combined to prevent the agglomeration of single metal atoms and overcome the problem of poor electrical conductivity. The as‐prepared M‐SAAs can be directly employed as self‐supporting electrodes for the electrochemical dechlorination of 1,2‐dichloroethane, and outstanding activity and stability are observed. Significantly, the Cu‐SAA with abundant Cu−N4 sites shows an extraordinarily high ethylene production rate of 446 µmol h−1, with a selectivity of 99% and Faradaic efficiency of 64%. Moreover, theoretical calculations are performed to demonstrate the selectivity and activity of different metal active sites. This study provides a new strategy to exploit highly effective SACs and offers an intensive insight into the mechanism of electrochemical dechlorination reactions. A series of metal–nitrogen–carbon single‐atom aerogels are developed via a new strategy and employed as self‐supporting electrodes for the electrochemical dechlorination of 1,2‐dichloroethane. The strategy can not only prevent the agglomeration of metal atoms, but also overcome the poor electrical conductivity caused by the binder. Therefore, the electrodes show outstanding performance with high ethylene production rate, selectivity, and Faradaic efficiency.