Voter turnout was 43.7%, according to data published on the Hungarian National Election Office website, short of the 50% participation required to make the referendum valid under Hungarian law.
Gulyás Gergely, the Vice-President of Hungary's ruling party, FIDESZ, nevertheless described the result as an "overwhelming victory" that demonstrated "unprecedented unity." He said that more than 90% of those who did vote supported Prime Minister Viktor Orban's "No" position.
In a Sunday evening television address, Orban said the European Union cannot force migration policies on Hungary and vowed to fight any efforts to do so.
"Can a democratic community [the EU] force its will to a member where 92% [of the voters] is against it? I promise, I will do everything so this can never ever happen," he said.
Earlier on Sunday, Orban told reporters that his government would "start to negotiate the modification of the Hungarian constitution" if the referendum fell short of the 50% turnout needed to make it valid.
Orban had spearheaded a campaign asking Hungarians to reject EU migrant quotas for the country. Before the referendum, advertisements blanketed airwaves painting migrants in a negative light. Leaflets distributed throughout the country, along with posters and billboards, warned of the dangers of accepting refugees.
"We lose our European values and identity the way frogs are cooked in slowly heating water," Orban said Friday. "Quite simply, slowly there will be more and more Muslims, and we will no longer recognize Europe."
"What we have seen so far from the people's migration have only been warmup rounds. The real battle is yet to come," he added.
Under the agreement with the European Union reached last fall, Hungary would have to accept 1,294 refugees.
"This is a piece of international PR," said John Dalhuisen, the Europe director for Amnesty International. "This is international marketing. He's selling himself as the ideologue of a radically different migration policy. You'd characterize (German Chancellor Angela) Merkel as being 'let them come' -- he's saying the solution to the refugee crisis, to the migration issues in Europe, is 'let no one come.'"
Last year, when a mass exodus of migrants from Syria, Iraq and other countries flooded the Hungarian border, strict measures like razor wire fences and "border hunters" were put in place.
In footage that went viral, a Hungarian camerawoman was seen tripping
refugees making a run for the border.
Hungarian riot police used tear gas and water cannons at the country's border with Serbia last year after a group of migrants attempting to enter the European Union broke through a barrier.
Hungary has recently erected a razor-wire fence that runs the entire length of the country's borders with Serbia and Croatia.
Migrants from the Middle East and southeast Asia often cross the Mediterranean and try to go through Greece, Macedonia, Serbia, Hungary and Austria in an attempt to reach Germany or other European countries known to be more welcoming to refugees.