In 1948, he ran for and won a seat in the
United States House of Representatives as a Democrat, representing . He resigned his seat on June 30, 1962, to run for mayor of Newark. He ran on a reform platform, defeating what he characterized as the corrupt political machine of
Leo P. Carlin, who had been mayor since 1953.
Corruption investigation Addonizio served as mayor from 1962 until 1970, when he lost his reelection bid. A state investigation into his administration commenced following the
1967 Newark riots that occurred during his tenure, which led to the discovery that he and other city officials were taking
kickbacks from city contractors. In December 1969, he and nine current or former officials of the municipal administration in Newark were indicted by a federal grand jury; five other persons were also indicted. In July 1970, the former mayor and four other defendants were found guilty by a federal jury on 64 counts each, one of conspiracy and 63 of extortion. In September 1970, Addonizio was sentenced to ten years in federal prison and fined $25,000 by U.S. District Court Judge
George H. Barlow for his role in a plot that involved the extortion of $1.5 million in kickbacks, a crime that the judge said "tore at the very heart of our civilized society and our form of representative government". Addonizio served around half of his ten-year sentence before being released on
parole. ==Death==