Henry Ramos Allup, 72, will be the first opposition politician to lead the National Assembly in 16 years following a landslide victory in legislative elections on 6 December.
Mr Ramos said he would ensure the assembly would act "as an autonomous power."
The newly elected lawmakers will take up their seats on Tuesday.
Mr Ramos Allup was chosen by opposition lawmakers in a secret ballot with 69 votes out of 111 cast, defeating 46-year-old Julio Borges of the Justice First party.
He is expected to be formally confirmed in the post when the lawmakers take up their seats.
Mr Ramos Allup is the secretary general of the social-democratic Democratic Action party, which has long been opposing the socialist government of President Nicolas Maduro and his predecessor in office, Hugo Chavez.
The government says Mr Ramos Allup is a member of Venezuela's "old guard". His Democratic Action was one of two parties that alternated in power for four decades before President Hugo Chavez was elected president in 1998.
But his supporters say the 72-year-old has the experience and political savvy to turn the National Assembly into a counterbalance to President Maduro's executive branch.
Mr Ramos Allup said the MUD opposition coalition, which won a two-thirds majority in the National Assembly, would show Venezuelans "a more democratic way forward".
Known for his sometimes confrontational style, he struck a surprisingly conciliatory note after his election.
"We represent an alternative. We are not going to be anti-establishment, rather an autonomous legislative power," he said.
"We ask people to watch us, to demand more of us, and keep an eye on what we do to make sure we honour our commitment," he added.
Nevertheless, the first session of the assembly is expected to be tense after the opposition coalition said all of its 112 members would take up their seats even though three have been suspended by the Supreme Court pending investigations into alleged voting irregularities.
Tension is also expected to be high around the National Assembly building, as both the opposition and the governing Socialists have called on their supporters to converge on the building.
Venezuelan opposition lawmakers have chosen a veteran politician as the new head of the country's legislative body.