Gardner followed the example of Ridgewell in switching from Villa to their local rivals because of his desire for regular first-team football.
It has paid dividends for both players and Gardner is now City's leading scorer after netting his ninth goal of the season in yesterday's 2-0 home success over Sunderland.
Blue nose: Gardner has been in fine form since making his switch across Birmingham to St Andrew's
Defender Ridgewell said: 'Craig is benefiting from playing regular football.
'It was difficult for him coming in and out of the side at Villa. It was like me. I wanted to come here after playing so much at Villa for a spell and then going onto the bench.
'I wanted to come here and play and Craig has done the same and you reap the rewards from playing football week in and week out. The goals he has scored have been vital and it was a big one to take us away from Sunderland at 2-0 and give us breathing space.'
Ridgewell added: 'It is a hell of a boost to have a midfielder who can score goals. He has got some vital ones this season. I was right behind Craig's shot for the second goal against Sunderland and it dipped and swerved.
'He has got a great strike with either foot and has produced some great strikes this season.'
Breathe easy: Gardner's goal rounded off Birmingham's win over Sunderland
Victory moved Blues ahead of the Black Cats in the battle for Barclays Premier League survival and the Carling Cup holders have taken seven points from their past three games.
Ridgewell is hoping City can secure safety sooner rather than later so they can fully enjoy their shock win over Arsenal at Wembley.
He said: 'With the way it has been since we won at Wembley, we haven't had the chance to appreciate what we achieved.
'We've won the cup but it hasn't really sunk in because of our league position. We want to celebrate it properly - and we will if we stay up.
'That is our main aim now. We've got six games left to make sure we stay in the Premier League so it becomes a really good season.'
Sunderland have taken only one point from nine games and their lengthy injury list was added to with striker Danny Welbeck suffering a hamstring setback.
Injury worry: Welbeck is a doubt for the Black Cats showdown with Wigan
It makes him a doubt for next weekend's crucial home clash with fellow strugglers Wigan.
Black Cats boss Steve Bruce said: 'We don't know how serious it is yet. Danny was hampered with it in the first half.
'We sincerely hope it is not serious but, knowing our luck the way it is at the moment, I would be amazed if he is not a doubt for next weekend. We've had a lot of big injuries. It takes its toll and we haven't been able to cope the last few weeks.'
Former Birmingham manager Bruce took consolation from an improved showing by his side at St Andrew's.
He said: 'We're all really disappointed but the positive is it was the best we've played in weeks - but we haven't got the result.
'The chances we created and the football we played didn't warrant us going back home with no points. You need a bit of luck, you need something to change, but I couldn't fault them in adversity.
'We've got a makeshift back four, we've got six or seven missing, but the young boys have come in and performed very well.
'We just need to get a result - and a result quickly - but if we keep playing like that, we will be okay.'
Birmingham winger Sebastian Larsson took advantage of hesitation by Sunderland goalkeeper Simon Mignolet to break the deadlock just before half-time.
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Explore more:People: Craig Gardner, Steve Bruce, Sebastian Larsson, Danny Welbeck, Liam Ridgewell Places: Birmingham