Zimmer spent the past five seasons as defensive coordinator for the Cincinnati Bengals. His name was mentioned often during the past few years in head coaching searches before he finally landed the job with the Vikings.
A deal was expected to be completed Wednesday. Zimmer interviewed in Minnesota on Tuesday and stayed overnight as contract negotiations continued, according to the ESPN report.
Zimmer will replace Leslie Frazier, who was fired after the 2013 season.
Before joining the Bengals, Zimmer was the defensive coordinator for the Dallas Cowboys from 2000 to 2006 and the Atlanta Falcons in 2007.