The mass rally took place to project their readiness in forming a new state in 2017
Hundreds of thousands of Catalans took to the streets of Catalonia demanding freedom from Spain on Sunday.
The mass rally comes as the pro-independence assembly vows to go ahead with plans of forming a new state in 2017, Reuters reported.
The march took place in five cities, including Barcelona where 540,000 people participated, police said.
The protests took place on their national day " La Daida" when Spain's King Philip V conquered Barcelona in 1714.
Catalans shouted "Ready" in Catalan, proclaiming they were ready to be free.
Head of the Catalan National Assembly, which organised the protest, Jordi Sanchez told the protestors, "This is the moment to stand united for the 'yes' to the Catalan Republic."
"We are impatient," he added.
However, Spain's government is opposing any move towards secession, creating obstacles through constitutional laws.
In 2015, the pro-separatist party won a majority of seats in the regional assembly and have now started laying the groundwork for an independent state.
Anti-independence campaigners told Reuters that the secessionists fell short of winning an overall majority of votes last year, which will weaken the mandate for separation.
A poll conducted in January showed 48 per cent were in favour of Catalonia becoming independent, while 42 per cent opposed it.
According to an AFP report, the call for separation strengthened after the 2012 economic crisis when many Catalans resented paying higher taxes to the Spanish government to aid the poorer regions.
Carles Puigdemont, head of the regional Catalonia government told journalists assembled at the rally, that in coming months "critical decisions" will be taken on Catalonia's future.
Analysts say Puigdemont will win the confidence vote in the Catalan assembly, which will take place on September 8.
(WION with inputs from agencies)