It’s a return for the club’s former midfield, who left to join Walsall with the understanding of the club’s fans in March 2018.
He left the Racecourse with the team in fourth place but now he is back with a different challenge on his hands.
The Dragons are only outside the National League bottom four on goal difference and a quick turn around is required.
Keates replaces Bryan Hughes who left following defeat to Aldershot Town late last month.
Dixie McNeil of the Wrexham Supporters Trust told the club’s website: “It’s really nice that he wanted to come back to the club and I hope that the Wrexham supporters will get behind Dean.
“Together we can turn this season around and I believe Dean can push us up the league table, although we are behind the play-off places at the moment, there are still over 90 points to play for.
“We talked to a number of people about the position, which we narrowed down to and then interviewed five people.
“Dean gave a very good interview and we decided he was by far the best person for the job.”