The Spanish government has stripped Catalonia of its autonomy and taken charge of its government.
The measures early on Saturday came after the Catalan parliament voted to declare independence on Friday.
An official state bulletin dismissed Catalan leaders and handed control of Catalonia to Spain’s Deputy Prime Minister, Soraya Saenz de Santamaria.
Earlier, Catalonia’s most senior police officials were dismissed by the Spanish government.
On Friday, PM Mariano Rajoy announced the dissolution of the regional parliament and the removal of the Catalan Leader, and called snap local elections.
Demonstrations for and against independence went on into the night.
More are expected on Saturday, with a rally “For the unity of Spain and the constitution” to be held in Madrid.
The crisis began when Catalan leaders held an independence referendum, defying a ruling by the constitutional court which had declared it illegal.
The Catalan government said that of the 43% of potential voters who took part, 90% were in favour of independence.
Others boycotted the vote after the court ruling.
On Friday afternoon, the Catalan regional parliament voted to declare independence from Spain.
Soon after, the Spanish senate granted Mr Rajoy’s government the power to impose direct rule on Catalonia.
Mr Rajoy said Mr Puigdemont and his cabinet would be sacked, the parliament dissolved and elections called.
Regional elections are scheduled for 21 December.
Mr Puigdemont urged supporters to “maintain the momentum” in a peaceful manner. Spanish prosecutors say they will file charges of “rebellion” against him next week.
Separatists say the move means they no longer fall under Spanish jurisdiction.
But the Spanish constitutional court is likely to declare it illegal, while the EU, the US, the UK, Germany and France all expressed support for Spanish unity.
Thousands celebrated the declaration of independence on the streets of Barcelona, Catalonia’s regional capital.
The same crowds that cheered each yes vote from Catalan mps reportedly booed Mr Rajoy as he made his announcement.
There were pro-unity demonstrations too, with protesters in Barcelona waving Spanish flags and denouncing Catalan independence.
A large pro-unity rally is expected in Madrid on Saturday.