The sentence's reduction was recommended by Justice Minister, Daniel Friedmann – as required by law.
Blumenthal was sentenced to eight months in prison after she was convicted for bribing Likud members before the 2002 primaries for the party’s leadership, in what came to be known as the "City Tower" affair.
Friedmann's recommendation was given to acting President, Knesset Speaker Dalia Itzik prior to Peres' taking office, but she refused to decide on the matter.
Following a petition by her children two months ago, a public campaign for Blumenthal's pardon began, led by public figures such as former minister Yossi Sarid and former President Yitzhak Navon.
Blumenthal's husband, Professor Michael Blumenthal, died earlier this year.
Her sentence was mitigated to two months probation and six months community service.