He takes over from Gerard Gallant, who was fired Monday. Agnew was promoted from his role as associate coach. The 46-year-old is in his first year with the Blue Jackets after serving as head coach of the American Hockey League's Syracuse Crunch the past six seasons.
The Blue Jackets will play their first game since the shuffle Wednesday at home versus the Nashville Predators.
Columbus is 5-9-and-1 this season.