He was accused of failing to stop his rebels from killing and raping people.
Bemba's lawyers have already said they will appeal against his conviction.
Judges announced sentences of between 16 and 18 years for five counts of rape, murder and pillaging, with the jail terms running concurrently. The eight years Bemba has already spent in custody will be deducted from his term.
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His conviction was the first time the ICC had focused on rape as a weapon of war, and the first time a suspect had been convicted for crimes committed by others under his command.
Passing sentence at the ICC in The Hague, Judge Sylvia Steiner said Bemba had failed to exercise control over his private militia sent into CAR, where they carried out "sadistic" rapes, murders and pillaging of "particular cruelty".
The BBC's Anna Holligan, who is in The Hague, says two key issues remain - where Bemba will serve his sentence and the amount of compensation to be awarded to his victims.
Bemba was "extremely disappointed" with the sentence, his lawyer, Kate Gibson, told AFP news agency.
"Today's sentence is by no means the end of the road for Mr Bemba, it merely signals that we are now moving to the next phase of the process which is the appeal," she said.
In 2002 Bemba had sent more than 1,000 fighters to the CAR to help then president Ange Felix Patasse put down an attempted coup.
The court heard that his troops committed acts of extreme violence against civilians - crimes which the judge said Bemba was made aware of but did nothing to stop.
He had led the MLC (Movement for the Liberation of Congo) rebel group during DR Congo's brutal civil war and after a 2003 peace deal he laid down his arms and joined an interim government.
Human Rights Watch (HRW) said the sentence offered "a measure of justice" for the victims.
"Other commanders should take notice that they, too, can be held accountable for rapes and other serious abuses committed by troops under their control," said Geraldine Mattioli-Zeltner, HRW's international justice advocacy director.
The MLC is now a major opposition party in DR Congo and Secretary General Eve Bazaiba criticised the ICC ruling and sentence.
"We will never cease denouncing the selective justice of the ICC," she told supporters in the capital Kinshasa.(BBC)