Corrie Ndaba has returned to Kilmarnock on a three-year deal following a successful loan spell last season.
The Irish defender leaves Ipswich Town for an unknown price after being with the newly promoted Premier League side since 2016.
Ndaba made 37 games for Kilmarnock, helping them finish fourth in the Premiership.
“I’ve always wanted to come to Kilmarnock,” the 24-year-old said on the Ayrshire club’s website.
“Other teams were interested, but I obviously have a strong relationship with the manager, and meeting with him helped me determine that this is a positive move in my career and will help me advance.
“Last season was the best of my career, we had a really good year and obviously qualified for Europe, I hope we can do that again.”
Kilmarnock go to Cercle Bruges for the second leg of their Europa League qualifier on Thursday, following a 1-1 draw at Rugby Park last week.