The Millers turned to the 54-year-old after a horrendous start to the season left the club rock bottom of the second tier with just six points from 13 games.
Jackett’s bow will come today at home to Reading and with United already six points adrift of safety, the task he faces is a big one.
Stewart, however, believes a CV that includes five seasons in the Championship with Millwall and Wolverhampton Wanderers can make all the difference.
“I am not looking for miracles,” said Millers chairman Stewart. “I am looking for a guy that knows what he is doing. Someone who can get the systems working like we have seen in the past and start making statements in the Championship, but more importantly getting the points that we feel we have lost.
“We are very excited to have someone who has the experience that he does in the Championship, and I think that will make a big difference as we move forward.”
Jackett met his new players for the first time yesterday before training.
It means time will have been short to get across his ideas to a side that has lost their last six games.
Despite that, Stewart is hoping the new manager can make an immediate impact.
He added: “I think it was crucial to get him in early because we have 11 games left before January, so he has time to take stock now and have a look and give opportunities to the players.”
The New Year, of course, is when the transfer window reopens and Stewart has promised Jackett funds to strengthen.
“He talked about that and said, ‘What about when the window becomes available?’
“We have had managers in the past that have had many, many players.
“As a board, we have always worked with the manager and we want what he wants. I am sure that when it comes to January he will be making certain demands and we are here to work with him to build a team that is sustainable not just for this season, but the next two or three.”
Jackett becomes Rotherham’s fourth permanent manager in a little over a year. Of those, only Neil Warnock made a tangible impact when inspiring the Millers to safety thanks to an unbeaten run of 11 games in the spring.
“I am sure people will get behind the guy and I know that it will be something to kick us on again,” added Stewart. “I, like the fans, didn’t like the results that we were getting,”
Football previews: Pages 2-5.