July 13th 2018: The 23-year-old right back arrives on a six-month contract after impressing during the pre-season training camps in La Manga and Largs.
After starting his career as a youth with Clyde and St Mirren, Ross made his breakthrough at Dunfermline Athletic in 2013.
Following spells with Livingston and Clyde, he made the move to Queen's Park under the guidance of Killie legend Gus MacPherson.
Two seasons with the Spiders followed before Ross, the son of Killie's U20s coach Andy, decided to return to full-time football.
Dec 29th 2018: Ross Millen has signed a new 18-month contract with Killie. The 24-year-old has been rewarded for his form over the past six months, which included the winning goal on his Premiership debut against then-league leaders Hearts at Tynecastle.
June 2020: Ross signs a new 1 year deal to stay at Killie.
June 1st 2021: Ross Millen has left Kilmarnock following the expiration of his contract.
Manager Tommy Wright said: “We set Ross a deadline to get back to us about a contract extension, giving him time to think it over. The club didn’t get a response in time and we’ve now withdrawn our offer. It’s important that we have players here who want to play for the club. I want to thank Ross for his time at Killie, and wish him well.”
The full-back will depart after three years at the club having joined Killie in July 2018.