After Kelly entered the plea Wednesday in Arapahoe County District Court, he was sentenced to one year of supervised probation and 50 hours of community service.
Kelly originally was charged with first-degree criminal trespassing, but that was dropped as part of a plea agreement with prosecutors.
According to court documents, Kelly entered a couple's home after 1 a.m. on Oct. 23, sat on their couch and mumbled incoherently.
Kelly, 24, had attended an annual Halloween party hosted by Broncos star Von Miller before the incident.
The Broncos released Kelly after his arrest. He has not signed with another NFL team.