Ukraine is the largest sovereign country located entirely in Europe.
Ukraine covers about 603,550 square kilometres, making it larger than France, Spain and Sweden when the comparison is limited to countries wholly within Europe. Its territory lies largely on the East European Plain and reaches the Black Sea and Sea of Azov.
The qualification “entirely in Europe” matters. Russia is geographically transcontinental and has a larger European portion, but most of its territory lies in Asia. France is also often ranked above Ukraine in broad country lists when overseas territories are included, while Turkey and Kazakhstan span Europe and Asia.
Ukraine’s modern borders and area are also discussed in the context of Russia’s annexation claims and the occupation of parts of Ukrainian territory. International rankings generally continue to treat those areas as part of Ukraine, so the country’s recognized area remains the basis for this answer.