The Finnish U21 international had limited time on the pitch for the first team last season but is looking to impose himself in the team in the coming season.
"I only managed a few short appearances last time around and it was great to be out there. The experience just makes you more hungry to get involved more. The fans are excellent here and I'd like to show them more." Koskela told the official website www.cardiffcityfc.co.uk
He has signed a 1 year deal.