But Fujimori could be released earlier if his daughter, Keiko Fujimori, is elected president in 2011.
Keiko Fujimori, who is leading some opinion polls as the election approaches, has said that she will grant her father a pardon if she becomes leader.
Prosecutors had accused Fujimori of ordering Vladimiro Montesinos, a former intelligence chief, to use state funds to secretly spy on 28 politicians, journalists and businessmen.
Fujimori was also accused of authorising bribes to be paid to 13 congressmen so that they would join his party, and allegedly bought off a TV station and a newspaper editorial board to support his re-election campaign in 2000.
Montesinos, who is serving a 20-year term for bribery and selling weapons to Colombian rebels, said during his own trials that he made the payments on Fujimori's behalf.
Fujimori said that he knew nothing of the money.
Fujimori, who was extradited to Peru from Chile in 2007, has also been convicted by a three-member panel of crimes against humanity for authorising military death squads, abuses of power, and of embezzlement.
In the embezzlement trial, in which he was found guilty of paying $15m in state funds to Montesinos, he admitted responsibility but said that he later repaid the money.
Fujimori is appealing against his previous convictions.
Fujimori first became president in 1990 in a democratic election but became increasingly authoritarian during his government's campaign against left-wing armed groups.