Turnout was 43 percent as Catalans who reject independence largely boycotted the poll.
They march while Spanish Prime Minister Mariano Rajoy has already warned that any declaration of independence by Catalonia will not affect Spain's unity.
Rajoy says he would only hold talks with Puigdemont's side if the Catalan separatists abandoned their independence bid in line with the Spanish constitution.
Ever since Spain's return to democracy in the 1970s, Madrid has struggled to balance the country's patchwork of regional identities, including its decades-long fight to quell separatism in the northern Basque Country led by violent militants ETA. Over 900 people and 33 police officers were injured during the clashes on Sunday.
Barcelona police said 350,000 people participated, while march organizer Societat Civil Catalana said 930,000 people turned out. He says he will address the regional parliament on Tuesday " to report on the current political situation". Madrid sent thousands of national police to the region to prevent the vote.
But now the tide seems to be turning. The boards of Catalonia-based infrastructure firm Abertis, telecoms company Cellnex and property group Inmobiliaria Colonial will meet on Monday to discuss moving, sources said.
Other companies took the same decision of leaving Catalonia such as Oryzon Genomics (which took the decision on Tuesday), Eurona, Proclinic, Arquia Banca, Service Point or Dogi.
Protesters on Sunday called for the imprisonment of Mr Puigdemont after he pledged to push for independence.
The final results from the wealthy north-eastern region showed 90 per cent of the 2.3 million people who voted backed independence.
European Affairs Minister Nathalie Loiseau said the crisis following the banned October 1 referendum had to be resolved through dialogue within Spain, BBC reported.
"Interventions were not aimed at citizens or their ideas, they were meant to prevent the holding of the referendum, the instructions transmitted by the highest court of the national territory", he said.
On Saturday, a similarly large rally was held in the city to demand secession from Spain, while another demonstration was held in support of Spanish unity in Madrid.
"And I hope as well that it will not go as far and Barcelona can continue to play in Spain".
Flag-waving demonstrators, calling themselves a "silent majority", packed central Barcelona on Sunday to protest against the independence plan. But the issue has deeply divided the northeastern region itself as well the Spanish nation. An AP reporter spoke with another man who had come from the northern Basque Country region. "We will do everything that legislation allows us to ensure this", Rajoy told the newspaper. "We want Barcelona to once again be the capital of Spanish culture".
The premier noted that 4,000 additional police were deployed in Catalonia in the run-up to the referendum, adding they would stay until the crisis was over.
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