Hereford's wide midfielder Paul Parry became a Cardiff City player on Friday after a successful medical.
Paul Parry impressed during a trial at Cardiff
The Bulls will receive an initial fee of £75,000 for the 23-year-old, who impressed on trial at Ninian Park.
"I am delighted. Paul will give us the width we need down the left," boss Lennie Lawrence told the club website.
"I have watched him on several occasions over the past few weeks, and we had the lad here on trial for four days and he impressed me."
Parry had also been a target for Yeovil, who made an offer for the player in September.
Cardiff finalised the deal on Friday afternoon in time for Parry to be available for Saturday's Division One match with Rotherham.
"He will go into the 16-man squad on Saturday," Lawrence said.
"You haven't got to be Einstein to work out that we lack a little bit of balance in our team at the moment with the absence of Robbo (John Robinson).
"The other thing to bear in mind is that he is at the top of his game at the moment - he is the best attacking player in the Conference - although we appreciate there is a huge gap between the Conference and Division One."