Crimeans in Simferopol and Sevastopol were seen already waiting for celebrations of the referendum outcome.
Most, when asked, expressed their confidence that this third referendum in the history of the peninsula would direct them "home" to Russia.
However, Western countries like the United States, France, Germany and Britain have rejected the referendum, calling the vote "illegal" and "contrary to Ukrainian Constitution."
US president Barack Obama said on Sunday that the United States will not recognize the Crimean referendum, vowing to impose fresh sanctions on Russia.
French Foreign Minister Laurent Fabius denied the legitimacy of Crimea's referendum, urging Russia to take immediate measures to avoid a "useless" and "dangerous" escalation of Ukrainian crisis.
Three days before the vote took place, German Chancellor Angela Merkel had warned Moscow that Europe could inflict "massive economic and political damage" to Russia if the situation in Crimea escalated.
"Nothing in the way that the referendum has been conducted should convince anyone that it is a legitimate exercise," British Foreign Secretary William Hague said in a statement after arriving in Brussels for the meeting of EU Foreign Ministers on Monday.
In a joint statement issued Sunday by European Council President Herman Van Rompuy and European Commission President Jose Manuel Barroso, the EU leaders said the referendum in Crimea was "illegal and illegitimate" and its outcome "will not be recognized."
Russian President Vladimir Putin, in separate phone calls with Obama early Monday and German Chancellor Angela Merkel on Sunday, said the ongoing Crimea referendum did not breach international law and was totally legal.
"Putin said the Crimean population's vote is proceeding in full compliance with international law, in particular with Article 1 of the UN Charter that stipulates the principle of equality and self-determination of peoples," the Kremlin website said, citing a telephone conversation between the leaders.
"Russia will respect the choice of Crimean residents," Putin said, adding that he was concerned about the aggravation of the situation in eastern and southeastern regions of Ukraine.
Despite different assessments of the situation in Crimea, Putin and Obama agreed to continue searching for ways of assistance to the stabilization of Ukraine.
The Crimea Peninsula, historically part of the Russian Federation, was transferred to Ukraine in May 1954, then a republic of the Soviet union .
In 1992, the Crimean Supreme Council (parliament) declared independence in May pending a referendum which was called off by the Ukrainian authorities.
Crimea held two other referendums in 1991 and 1994, testing voters' preference for greater autonomy within Ukraine or uniting with Russia.
The same supreme council decided on March 6 to hold the peninsula's third referendum which was originally scheduled for March 30 after the Ukrainian authorities decided to annul Russian as the official language in the peninsula.
The Crimean Supreme Council passed a resolution of declaration of independence on March 11 to pave the way for Sunday's referendum.
