"There's no doubt about the culpability of the defendant", presiding judge Oliver Ottmann said during sentencing.
But Ottmann didn't hand down the maximum penalty requested by prosecutors, saying that the man had shown "understanding of his crime and remorse".
The 51-year-old defendant confessed to having sent Hoeneß, currently serving a jail term for tax fraud, a letter warning that his time in prison would be "no picnic" unless he paid up, a court spokeswoman said.
"The defendant made a full confession," the spokeswoman for the regional court in Munich said on the opening day of the court case.
Signed Mister X, the blackmail note demanding €215,000 was posted to Hoeneß' private address in May before he went to prison and immediately handed to the police by Hoeneß' wife.
The defendant had previously served prison sentences himself and claimed in the letter he had "real influence" over how Hoeneß' time in jail could go.
"The defendant indicated as a motive for the act his own financial need," the spokeswoman said.
He also felt that Hoeneß had come away more lightly in his sentence than he himself had earlier done.
Prosecutors had asked for up to five years in prison before the verdict.
Hoeneß, 62, who spent four decades at Bundesliga champions Bayern Munich and also has a successful sausage business, began a three-and-a-half year jail term in June for having cheated the state out of €28.5 million.
At his four-day trial several months earlier, he admitted hiding his wealth in secret Swiss bank accounts while obsessively "gambling" on stock and currency markets.
Hoeneß and his wife will not be called as witnesses in the blackmail trial due to the defendant having confessed, the spokeswoman said.
In a statement read by his lawyer, the accused said he was a diabetes patient who could no longer afford health insurance after being 340,000 euros in debt.
"I found myself at that time in a completely hopeless situation."
When he heard about Hoeneß sentence for millions of euros of tax evasion seemed "monstrous" compared with his own sentence. "The idea came to me spontaneously, touched off by my completely desolate situation."