William Lara, who heads President Hugo Chavez's Fifth Republic Movement, said his party will control 114 seats as a result of the vote, with the rest going to parties that support the president.
He insisted that after January 5, when the new legislature is inaugurated, Venezuela will still have a "multi-party National Assembly, which will include various civic groups and independent deputies."
His National Assembly majority means President Chavez will now be able to end presidential term limits and seek re-election next year.
The National Electoral Council earlier said only about 25 percent of 12 million registered voters cast their ballot, after main opposition parties including Democratic Action and COPEI boycotted the poll after accusing electoral authorities of favouring the populist leader and manipulating electronic voting machines.
However Jorge Rodriguez, president of the National Electoral Council, explained the low turnout as due to "torrential rains that have prevented voters from getting to polling places."
"The voting went ahead with absolute normality," he said.
"We can say the Venezuelans have expressed their opinion today as established by the Constitution."
Hundreds of foreign election monitors from the European Union and the Organisation of American States declared the vote legitimate, however opposition groups said there were plenty of irregularities.
One complaint was that electronic voting machines used in Sunday's vote could record fingerprints, allowing authorities to know how each person voted, although election officials agreed to switch that feature off.
President Chavez, a leftist-populist former paratrooper and close ally of Cuba's communist leader Fidel Castro said old parties are refusing to die, in reference to Democratic Action and COPEI, which alternated power in the country for 40 years until 1998, when he was elected.
Election violence
There were some reports of election-related violence, including an oil pipeline that was set ablaze at two points, described as an act of sabotage by the military.
Interior Minister Jesse Chacon said explosives were used to blow up the pipeline.
"We already know who is behind this situation and we have made some detentions," he said.
Energy Minister Rafael Ramirez said the fires would not cause any fuel shortage.
Venezuela is Latin America's only OPEC member.