The Istat data agency figures also revealed 2013 was the worst year in terms of employment of an economic crisis which has dragged on since 2008 in Italy, with the number of employed people falling by 478,000.
Between 2008 and 2013, the total number of people with jobs in Italy has fallen by 984,000, Istat said.
The overall unemployment rate of 12.9 percent was the highest since monthly figures began to be kept in 1977.
The news comes one month after Istat reported that Italy's unemployment rate reached a record high of 12.7 percent in November from 12.5 percent in October.
Last week, Matteo Renzi said unemployment would be a priority of his government, just after receiving the nomination to be the country's new prime minister.
"The most pressing emergency, which concerns my generation and others, is the emergency of labour, of unemployment and of despair," the 39-year-old said.
"I will put all my energy, enthusiasm and commitment into this difficult situation."