The Catalan regional parliament voted 70-10 to create “a Catalan republic as an independent and sovereign state”, with two ballots left blank.
The central Government’s jack-booted handling of Catalonia – and it’s bid for independence as long ago as the 1930s – is seen as one of the triggers of the Spanish Civil War which broke out in 1936.
Some Spaniards fear today’s declaration of independence could once more see Spaniards taking arms up against their fellow countrymen.
The Spanish Civil War left more than 500,000 dead.
Dozens of opposition MPs refused to take part in the ballot, with some leaving Spanish and Catalan flags on their empty seats.
Almost simultaneously, the Spanish parliament voted to impose Article 155 and to impose direct rule over Catalonia.
The main secessionist group in Catalonia has called on civil servants not to follow orders from Madrid, and to respond with “peaceful resistance”.
Shortly before the results were announced, Spain’s Prime Minister Mariano Rajoy asked for “all Spaniards to stay calm”.
Catalan leader Carles Puigdemont has urged supporters to “remain peaceful”.
He tweeted: “The rule of law will restore legality in Catalonia,” and announced that a cabinet meeting would be held at 5pm BST (6pm local time).
If Article 155 is triggered, Mr Puigdemont and his government could be removed from power tomorrow.
If independence is declared, Mr Puigdemont could be arrested on charges of treason, Spain’s public prosecutor has said.
Political and military analyst Sara Plana has said that Catalan independence could “reveal the fragility of the project of Spanish governance”, which is why she says “the state may be willing to go to war to preserve it”.
Speaking to The Sun, she said that the conflict has echoes of the Yugoslav wars which killed 140,000.
“In perhaps the most alarming parallel to Yugoslavia, a number of nations within Spain have separatist aspirations, and an independent Catalonia could be just the first of many dominoes to fall,” she said.
Spain has been in crisis since October 1, when Catalonia held an independence referendum.
Officials said that 90 per cent of the 2.26 million who voted in the referendum chose Yes, with turnout pegged at 42.6 per cent of the electorate.
Madrid insisted that the referendum was illegal, and sent police into Catalonia who violently shut down polling stations.
Since then there has been widespread unrest, with thousands of Catalan citizens protesting against the police violence.