During Thursday morning's hearing, Diamond also got 15 months probation, and cannot return to the scene of the crime or contact the victim. However, he was ordered to pay the victim $1,105 in restitution.
The "Saved by the Bell" star will serve his 120 days in two 60 day stints.
Diamond was arrested in December 2014 for stabbing a man during an bar altercation on Christmas night. He was convicted of carrying a concealed weapon and disorderly conduct ... both misdemeanors.
During sentencing, the judge admonished Dustin for even carrying a knife -- since Wisconsin's such a safe place.