Catalonia's leader says the region has won the right to statehood following Sunday's contentious referendum, which was marred by violence.
Regional president Carles Puigdemont said the door had been opened to a unilateral declaration of independence.
Catalan authorities said 761 people were hurt as police used force to try to stop the independence vote.
The Spanish government had pledged to stop the poll, which was declared illegal by the country's constitutional court.
Police officers prevented some people from voting, and seized ballot papers and boxes at polling stations.
The Catalan government said around 2.26 million people had cast a ballot and 90 percent of them had voted in favour of secession.
This represented a turnout of around 42.3 percent of Catalonia's 5.34 million voters.
"We have won the right to have an independent state in the form of a republic," said Mr Puigdemont in a televised address flanked by other senior Catalan leaders.
Earlier, as voting ended, Spanish Prime Minister Mariano Rajoy said Catalans had been fooled into taking part in an illegal vote. He called it a "mockery" of democracy.
Vote marred by violence
In the regional capital Barcelona, police used batons and fired rubber bullets during pro-referendum protests.
Barcelona's Mayor Ada Colau condemned police actions against what she said was the region's "defenceless" population.
Meanwhile, the Spanish interior ministry said 12 police officers had been hurt and three people arrested. It said 92 polling stations had been closed.
The national police and Guardia Civil - a paramilitary force charged with police duties - were sent into Catalonia in large numbers to prevent the vote from taking place.
New York Times Spain correspondent Raphael Minder told Morning Report there was a parallel story out of Madrid that is it had dismantled the referendum.
"[But] Catalans tell us that in 90 percent of the cases voting went ahead as normal, and along the way hundreds of people got injured," Mr Minder said.
The deadline for voting was 8pm (local time, 18:00 GMT), but a Catalan government spokesman said that anyone in the queue at that time would be allowed to vote.
- Catalan leader Carles Puigdemont said: "The unjustified use of violence ... by the Spanish state will not stop the will of the Catalan people"
- Spain's Deputy Prime Minister Soraya Saenz de Santamaria said police had "acted with professionalism and in a proportionate way"
- Spanish Interior Minister Juan Ignacio Zoido blamed Mr Puigdemont for what he termed the day's senseless events
- The Guardia Civil said it was "resisting harassment and provocation" while carrying out its duties "in defence of the law"
One voter, Júlia Graell, told the BBC that "police started to kick people, young and old", adding: "Today, I have seen the worst actions that a government can do to the people of its own country."
In Girona, riot police smashed their way into a polling station where Mr Puigdemont was due to vote, and forcibly removed those looking to place their ballots.
Mr Puigdemont was able to vote at another polling station.
The BBC's Tom Burridge, in Barcelona, witnessed police being chased away from one polling booth after they had raided it.
Since Friday, thousands of people have occupied schools and other buildings designated as polling stations in order to keep them open.
Many of those inside were parents and their children, who remained in the buildings after the end of lessons on Friday and bedded down in sleeping bags on gym mats.
In some areas, farmers positioned tractors on roads and in front of polling station doors, and school gates were taken away to make it harder for the authorities to seal buildings off. Firefighters have acted as human shields between police and demonstrators.
Referendum organisers had called for peaceful resistance to any police action.
Meanwhile, FC Barcelona's match against Las Palmas was played behind closed doors, after Barcelona said the football league refused to suspend the game.
Why is a vote being held?
Catalonia, a wealthy region of 7.5 million people in north-eastern Spain, has its own language and culture.
It also has a high degree of autonomy, but is not recognised as a separate nation under the Spanish constitution.
The ballot papers contain just one question: "Do you want Catalonia to become an independent state in the form of a republic?" There are two boxes: Yes or No.
Pressure for a vote on self-determination has grown over the past five years.
But Spanish unionists argue Catalonia already enjoys broad autonomy within Spain, along with other regions like the Basque Country and Galicia.
Why is Madrid so opposed?
Spanish Prime Minister Mariano Rajoy said says the vote goes against the constitution, which refers to "the indissoluble unity of the Spanish nation, the common and indivisible homeland of all Spaniards".
Central government spokesman Iñigo Mendez de Vigo accused the Catalan government of being inflexible and one-sided, but it is a charge that Catalan nationalists throw back at Madrid itself.
Before Sunday, demonstrations by independence campaigners had been largely peaceful.
Thousands of extra police officers were sent to the region, many of them based on two ships in the port of Barcelona.
The Spanish government has put policing in Catalonia under central control and ordered the regional force, the Mossos d'Esquadra, to help enforce the ban on the illegal referendum.
Before the poll, Spanish authorities seized voting materials, imposed fines on top Catalan officials and temporarily detained dozens of politicians.
Police have also occupied the regional government's telecommunications centre.