The appointment of Matjošaitytė, a lawyer by education, was on Thursday approved by 74 of Lithuania's 141 lawmakers, 12 were against and two abstained in a secret ballot.
Opposition conservatives did not cast their ballots in protest of refused appointment of the party's politician Vilius Semeška to the Central Electoral Commission.
Semeška was excluded from the resolution by decision of the Committee for State Governance and Municipalities as falling short of legal requirements.
The Central Electoral Commission consists of candidates proposed by the justice minister, the president and the Lithuanian Society of Lawyers, as well as members delegated by political parties with most mandates in multi-mandate voting.
Zenonas Vaigauskas, the commission's current chairman, had been heading the body for more than two decades.