The legislature passed an independence declaration during an extraordinary session, proclaiming the Black Sea peninsula an independent sovereign state, the Republic of Crimea, Xinhua reported.
Crimea's Supreme Council also formally sent application to Kremlin for joining the Russian Federation as a new republic.
Earlier in the month, the Crimean parliament voted to become part of Russia and passed a resolution of declaration of independence paving the way for Sunday's referendum.
Ukrainian authorities have dismissed the referendum as "illegal," saying it violates the country's constitution.