He had decided to plead guilty to nine felony counts, including wiretapping and unauthorised access to protected computers - and prosecutors had recommended 71 months in prison combined with a high fine.
But Los Angeles District Judge S James Otero decided to go for a more harsh custodial sentence with lower financial penalties.
Chaney, 35, had accessed and shared naked images of ScarJo which had been meant for her then hubby Ryan Reynolds.
He had also procured nude snaps of Christina by accessing her stylist's email account and requesting the revealing snaps from the star.
In total he accessed the email accounts of 50 people, including two non-celebs who the judge noted he had stalked for more than 10 years.
The verdict was announced in a press release, in which the FBI's Bill Lewis said: "Mr. Chaney methodically targeted his victims based on their celebrity without regard for the law or the impact the theft of personal and intimate details would have to their lives.
"This case illustrates the need for cybersecurity vigilance by computer users and, in addition, may serve as a deterrent for anyone contemplating similar intrusions."