The non-binding resolution was passed on Wednesday by 85 votes in favor, 41 against, and two abstentions, the Associated Press reported.
The declaration, which states that the people of Catalonia have a democratic right to decide on their sovereignty, sets up a potential showdown with the central government in Madrid.
Catalonia, one of the most developed regions in Spain, already enjoys a wide degree of autonomy, but the country’s economic crisis has fuelled Catalan nationalism.
Growing Catalan separatism is a huge challenge for Spain’s conservative Prime Minister Mariano Rajoy, who is trying to avoid getting bailed out by its European Union neighbors.
Rajoy says a referendum on secession is unconstitutional and hurts all Spaniards, who are already suffering in a recession with the unemployment rate higher than 25 percent.
The approximate 16 billion euros Catalonia pays Madrid in annual taxes is more than it gets back from the central government.
In addition, the autonomous region owes around 40 billion euros in debt, which has forced regional authorities to introduce spending cuts in healthcare and education.
Many Catalans believe their economy would be more prosperous on its own, complaining that a high portion of their taxes goes to the central government in Madrid.
Catalonia, which consists of Barcelona, Girona, Lleida, and Tarragona, accounts for one-fifth of Spain’s economic output.
Spain’s 17 autonomous regions manage their own budgets and are responsible for health and education policies and other areas of public spending.
Battered by the global financial downturn, Spain’s economy collapsed into recession in the second half of 2008, taking with it millions of jobs.