The National Electoral Board took the decision to strip regional Catalan President Quim Torra of his seat after a Catalan court barred him last month from public office during 18 months for disobedience.
Both of Spain's likely partners in government want to maintain Catalonia's position as an integral part of the country.
The second election in six months saw Spain’s political landscape become more fractured than ever before as the ruling Socialist Party lost seats, the far-right Vox party more than doubled its seats and nobody managed an overall majority.
Far-right party Vox became the third-largest party in Spain's parliament following a national election on Sunday, winning 52 seats, up from 24 at its debut in April.
Around 80,000 people marched through the streets of Barcelona to show support for Spain a day after the city hosted two pro-independence protests.
Catalonia has been gripped by unrest since an October 14 Supreme Court verdict found 12 Catalan leaders guilty of sedition and other crimes.
Hundreds of people packed a square in front of Catalonia's regional government headquarters in Barcelona for a rally by the centre-right, pro-union Ciudadanos party.
"This cannot continue. Barcelona does not deserve it," Mayor Ada Colau told reporters, adding that Friday's violence was the worst so far.
It was the biggest gathering since Monday's explosive verdict, which had already brought tens of thousands of independence supporters onto the streets in protest in this wealthy northeast region.
Carles Puigdemont handed himself in after Spain issued a new warrant for his arrest following the sentencing of 12 of his former colleagues. Thousands gathered in Barcelona, Spain on Friday to protest the jailing of the separatist Catalan leaders.
Young people draped in Catalan flags congregated peacefully, tossing balls and skipping rope. Later the mood turned ugly, with protesters setting fire to cafe chairs on the fashionable Rambla de Catalunya street at the heart of the tourist district.
Pro-independence regional chief Quim Torra says a new vote would have to be held to decide on self-determination for Catalonia, as more than 100 protesters were injured in overnight clashes.
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