"Crimea has de facto become part of Russia. This is a de facto situation and we will support Russia," Lukashenko said adding that the de jure recognition will come later.
Russian President Vladimir Putin signed a decree Friday on the ratification of the treaty providing for the reunification of the Crimean Peninsula with Russia.
The treaty was signed with Crimean Prime Minister Sergei Aksyonov and other leaders of the region on Tuesday and ratified by both houses of the Russian parliament.
Leaders in the predominantly Russian-ethnic republic refused to recognize the legitimacy of the government in Kiev that came to power amid often violent protests last month, instead seeking reunification with Russia.