The controversial star had his prison term reduced by one year by a federal judge, after he was convicted in a murder-for-hire plot against Carole Baskin.
Joe - whose real name is Joseph Maldonado-Passage - was resentenced after a federal appeals court determined in 2021 that improper sentencing guidelines were previously used.
The former zookeeper was initially sentenced to 22 years in prison. But his attorneys campaigned to have his sentence reduced, alleging "imperfect entrapment, sentencing manipulation, and outrageous government conduct".
In a sentencing memorandum, they previously said: "From decisions made in the initial stages of the investigation to charging decisions to overzealous sentencing recommendations, one thing remains clear: this case was about doing whatever it took to put Mr Maldonado-Passage behind bars for as long as possible."