Joe Ralls will play Championship football for Yeovil for the first half of the season.
Ralls's move was rubber stamped today and he will be available for Yeovil's match against Burnley on Saturday.
He follows Ben Nugent of the club in the past week or so. Nugent joined Brentford on loan.
“Both Ben and Joe have gone out on loan to gain experience,” said manager Malky Mackay. “They remain very much part of things here at Cardiff.”