In 2015, during his fourth term, Mazăre resigned amid accusations of corruption, citing the unbearable stress caused by what he claimed to be politically motivated investigations.

In November 2008, The Diplomat reported that the National Anti-corruption Department had accused Mazăre, along with 36 other municipal employees, of corruption, abuse of public service, forgery, and criminal complicity.

[7] Two days later he issued a public apology to Jewish organisations, declaring that by wearing the uniform he wanted to pay homage to Claus von Stauffenberg, a leading member of the failed plot to kill Adolf Hitler during World War II.

[8] Radu Mazăre in the year 2003 introduced the "tax for increasing the degree of peace and security in carrying out economic activities in Constanța, Mamaia and Sat Vacanţa" (taxa pentru creșterea gradului de liniște și siguranță în derularea activităților economice în Constanța, Mamaia și Sat Vacanță).

[12] The tax remained uncontested until 2015, when the president of the ACIA, civic activist Andrei Popescu, initiated a campaign to collect signatures to end this abuse.

[18] In May 2018, Mazăre received a six and a half-year prison sentence for abuse of power in a case related to the sale of a 15,000 sqm-plot of land in the Mamaia resort, subject to appeal.