The country's Supreme Court had ordered 12 of the men to begin their sentences immediately, the BBC reported Friday.
The group of politicians, bankers and businessmen were convicted last year in the so-called Mensalao, or "big monthly allowance," scandal.
Jose Genoino, a former president of the ruling Workers' Party, was the first to surrender to police to begin serving his six-year, 11-month sentence.
Genoino released an open letter protesting his innocence. While saying he was abiding by the Supreme Court's order, he asked "What do they accuse me of? There is no evidence."
Jose Dirceu, the former chief of staff to former president Luiz Inacio Lula da Silva, also turned himself in to police. In a statement, Dirceu protested "the unfair nature of the conviction against me." He has been sentenced to 10 years and 10 months in prison.
The convictions revolve around accusations that surfaced in 2005 that illegal payments were made to lawmakers in exchange for their votes on crucial issues.
While the scandal tarnished Lula's administration, he was not implicated in any wrongdoing.
Politicians in Brazil enjoy some measure of immunity from prosecution, and appeals often keep defendants out of jail for years, The Wall Street Journal reported. Brazilians have tired of corrupt leaders and the Mensalao case was of such a scale that some of the protections were lifted.
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