The 26-year-old has signed a one-year deal with the Rugby Park side.
Naismith spent part of the 2019/20 season on loan at Easter Road, making 14 appearances before injury curtailed his campaign.
He impressed Hibs fans with some rampaging performances down the right.
The defender returned to Ross County last season, helping the Staggies stay in the Premiership.
He has now joined Kilmarnock after their relegation to the Championship as Tommy Wright rebuilds the squad.
“I’m raring to go,” he told the Killie website. “My mind was made up as soon as I spoke to the manager and I wanted to be part of what he is building. I’m looking forward to my time here.
“You are always learning as a player and I’m excited to work with the manager. I’m still young in football terms and there’s obviously so much potential at this club.
“I can’t wait for the season to get underway.”