The enhancement in methane production under cold climates is one of the essential prerequisites to enable year-round performance improvement of any biogas plant. In Egypt, the winter is reasonably cold which offers a good opportunity to study the enhancement in the methane yield and corresponding performance improvement of a family-scale biogas digester using the co-digestion technique. This work reports the field performance of floating-dome type biogas digester using anaerobic co-digestion (AcoD) of cattle manure (CM) with a milled corn stover (CS). The performance of AcoD is compared with the performance of anaerobic mono-digestion (AmoD) of CM under winter conditions. Moreover, a numerical method for preparing the digested slurry is defined for the ease of the farmers. Results revealed that using AcoD was led to a significant increase in the average daily, cumulative, and specific methane yield by 40.30, 42.43, and 39.65%, respectively over AmoD. Additionally, AcoD gave an explicit increment in the average methane volume, average daily, and total gained biogas energy by 11.42, 40.16, and 42.43%, respectively over AmoD. Hence, the major findings of the present work proved that the co-digestion of CM and CS improves the performance of biogas digester under open-field conditions in the winter season.