The team announced the signing of Davis on Thursday after placing rookie linebacker Troy Dye on injured reserve with a foot injury.
Dye, a 2020 fourth-round pick, suffered the injury in the second quarter of the Vikings' 28-11 loss to the Indianapolis Colts on Sunday. In that game, he was filling in for Pro Bowl linebacker Anthony Barr, who tore his right pectoral muscle at the end of the first quarter and was placed on injured reserve Monday.
Barr is expected to miss the remainder of the season due to the injury.
With Dye and Barr injured, the Vikings decided to bring in Davis to help with depth. The 28-year-old linebacker started at least 14 games for the Broncos in each of the last four seasons.
Davis spent the off-season with the Broncos but was released Sept. 4. He wasn't on an NFL roster for the first two weeks of the season.
Davis led the Broncos in tackling last season and finished tied for eighth in the league with a career-best 134 total tackles in 14 games.
The Vikings are down to All-Pro Eric Kendricks, Eric Wilson, Ryan Connelly, Hardy Nickerson Jr. and Davis on their active roster. Nickerson was promoted from the practice squad earlier this week.