 From 1943 he developed the concept of the distinct establishment and development of Ukrainian and, later, Belarusian languages.Shevelov argued against the commonly held view of an original, unified East Slavic language from which Ukrainian, Belarusian and Russian languages diverged and instead proposed the existence of several dialectical groups (Kieven-Pollisyan, Galician-Podolian, Polotsk-Smolensk, Novgorodian-Tversk, Murom-Ryazansk) that had been distinct from the beginning and which later formed into separate Ukrainian, Russian and Belarusian languages.According to Shevelov, the beginnings of a separate Ukrainian language could be traced to the 7th century while the language formed in approximately the 16th century 

On 4 September 2013 memorial plaque to Shevelov in his native Kharkiv was unveiled.