Markus Reichel had admitted to handing over documents to the CIA, including names and addresses of agents for the Federal Intelligence Service (BND), in exchange for €95,000.
He had also delivered three classified documents to the Russian secret service.
Reichel's case had emerged during a furore over revelations of widespread US spying in documents released by former CIA intelligence contractor Edward Snowden, which had also plunged its partner service the BND into an unprecedented crisis.
Partially disabled after a botched childhood vaccination, Reichel, who speaks haltingly, had admitted that he had spied for foreign services out of dissatisfaction with his job at the BND.
"No one trusted me with anything at the BND. At the CIA it was different," he told the court at the opening of his trial in November.
Not only did the CIA offer "adventure", the Americans also gave him what he craved -- recognition.
"I would be lying if I said that I didn't like that," he told the court.
The former BND agent had joined the German service in late 2007, and drew a monthly net pay of 1,200 euros as a member of staff in the lowest salary band.
The CIA did not pay him significantly more -- he received between 10,000 and 20,000 euros a year in cash at a secret meeting point in Austria.
Reichel was still working for the BND until his arrest on July 2 last year.