With nearly all votes counted Sunday, the Junts Pel Si (Together For Yes) alliance won 62 seats in the 135-member regional parliament, and another pro-independence party, Candidatura d'Unitat Popular (CUP), won 10 seats.
But the pro-independence parties between them failed to win an overall majority of the votes cast, ending up with just under 48%.
The turnout -- at 77% of just over 5 million eligible voters -- was the highest in Catalan elections since the time of Francisco Franco.
Artur Mas, president of the Catalonian government, told a rally in Barcelona as the results came in: "Today we have a double victory. The yes vote has won, and what's more democracy has won."
Junts Pel Si pledged before the vote that if it won a majority in the assembly it would begin an 18-month process toward a unilateral declaration of independence for Catalonia, Spain's richest region.
But there's no guarantee Mas will be able to attract the leftist CUP into a formal coalition. The leader of the CUP, Antonio Banos, has been critical of Junts Pel Si and of Mas.
"The president of Catalonia has to be a leader by consensus, and Mas is not," Banos said last week.
The failure of the pro-independence parties to win an absolute majority of votes cast may restrain them from pressing forward immediately with unilateral moves toward independence, a process fraught with political and economic risks.
The European Union has said an independent Catalonia would have to apply for membership. Several European leaders, including British Prime Minister David Cameron, have spoken in favor of Spain remaining united. And during a visit to the United States by King Felipe of Spain earlier this month, President Obama said the United States was "deeply committed to maintaining a relationship with a strong and unified Spain."
Spanish Prime Minister Mariano Rajoy, who leads the conservative Popular Party, has said secession by Catalonia would be unconstitutional. He told a rally last week that Catalonia needed a new face of normalcy, after three sets of elections there in five years. And he accused the pro-independence parties of doing nothing but promoting tension, uncertainty and division.
"What would happen with financial institutions, what would happen with bank deposits, to the currency?" he asked in a radio interview.
Catalonia, which includes Barcelona, has long complained that its revenues subsidize other parts of Spain. It includes some 16% of the Spanish population and much of Spain's manufacturing and finance sectors.
The vote in Catalonia will complicate parties' calculations ahead of the general election, due early in December.
Polls suggest that no party will command a majority in the vote and analysts expect tough bargaining on forming a new coalition. To be viable, such a coalition may even need support from one of the Catalan parties.
Antonio Roldan Mones of the political risk group Eurasia, predicts: "The first thing the new government in Madrid will do following parliamentary elections is start a negotiation to reform the balance of powers among Spain's regions, probably involving a constitutional reform."
The opposition Socialists in Madrid have indicated that they may support constitutional changes.
Spanish regions already have considerable power in healthcare, education and tax collection, but the wealthier areas believe complex mechanisms for redistributing tax revenue are unfair. Even so, any further amendment to the constitution would open up a litany of grievances.