In front of 2,481 supporters, Wes Thomas scored a double for the Blues and Clayton Donaldson came off the bench to grab the third.
The victory makes it three wins and three clean sheets in as many games for Lee Clark’s men.
Kidderminster suffered an early loss when Marvin Johnson hobbled off injured and was replaced with Ahmed Obeng.
Thomas made the first impact in the 37th minute, when Gary Cotterill made a defensive header from a Kidderminster corner and sent Thomas down the line to beat keeper Danny Lewis.
Lee Novak set up Thomas for his second just 26 seconds into the second half, passing from the right hand side.
Donaldson was one of 13 combined substitutions and converted Mitch Hancox’s cross later in the second half to seal the win.
Blues boss Clark was happy with the result and said continuing with clean sheets is something for the team to aim for.
"I thought we’ve done lots of good things today,” he told the club’s official website.
"There are one or two situations that we need to brush up on but all in all I’m happy with the performance.
"The lads coped with it well, passed the ball about well at times and scored some good goals. It shows the power and the pace that we have at the top end of the pitch now."
Birmingham City begin their 2014/15 season on 9th August away at Middlesbrough.