And the central defender admits that without his appointment, with just three games of the 2016/17 campaign remaining, it would have been 'ten times harder' for Blues to survive.
Redknapp oversaw a six-point haul with victories over Huddersfield Town and Bristol City in their remaining two games, which enabled Blues to finish two points above the drop zone.
"Him (Redknapp) and Steve (Cotterill) have been brilliant from the moment they came in," said Shotton.
"They lifted everybody and I think without them it would have been ten times harder."
Shotton continued: "It was a case of getting the confidence back.
"We'd had four months where we'd only won two games in 24 and the lads just couldn't get going.
"They didn't feel we were fit enough and sharp enough in the training that we did.
"He just came in and made it shorter and sharper and intense to get our physical battling back, but with three games left they had a massive job to get us going."
The centre-half also paid tribute to the Blues supporters for sticking with the team during a difficult period.
"The fans have been absolutely brilliant in these times where we've had to dig deep," he said.
"We've done it all together as a football team, as a squad, and as a community in Birmingham and they've stuck by us.
"Against Huddersfield when we got the result they were the 12th man and against Bristol they never stopped.
"They've been behind us every second and that's what's made us pull through and I just want to thank them.
"We have a little break and go again next season now."