Efficient and selective earth‐abundant catalysts are highly desirable to drive the electrochemical conversion of CO2 into value‐added chemicals. In this work, a low‐cost Sn modified N‐doped carbon nanofiber hybrid catalyst is developed for switchable CO2 electroreduction in aqueous medium via a straightforward electrospinning technique coupled with a pyrolysis process. The electrocatalytic performance can be tuned by the structure of Sn species on the N‐doped carbon nanofibers. Sn nanoparticles drive efficient formate formation with a high current density of 11 mA cm−2 and a faradaic efficiency of 62% at a moderate overpotential of 690 mV. Atomically dispersed Sn species promote conversion of CO2 to CO with a high faradaic efficiency of 91% at a low overpotential of 490 mV. The interaction between Sn species and pyridinic‐N may play an important role in tuning the catalytic activity and selectivity of these two materials. A tunable Sn modified N‐doped carbon nanofiber hybrid catalyst is developed for aqueous CO2 electroreduction. It can efficiently catalyze CO2 to formate or CO by the selective presence of Sn nanoparticles or atoms on the surface of pyridinic‐N doped carbon nanofibers. This work may promote the development of nonprecious electrocatalysts for switchable conversion of CO2 to valuable products.