FREMANTLE defender Garrick Ibbotson has made the surprise decision to retire at the end of the season.

The 29-year-old was coming out of contract this year and seemingly faced an uncertain future after being dropped to Peel after the Dockers' 100-point round-10 loss to Adelaide.

But on Tuesday he broke the news to his teammates that he will hang up the boots after the Thunder's WAFL finals campaign.

"When you are looking at guys faces and telling them you are going to be out the door next year, it was never going to be easy," Ibbotson said.

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"But as hard as it is to leave a football club, I think it’s the right time for me and I am happy with my decision."

Ibbotson played 177 games and booted 22 goals for Freo after being drafted with pick 26 in 2005.

He enjoyed a career-best campaign in 2015 as an intercept half-back flanker as the Dockers won the minor premiership and he was named in the 40-man All Australian squad.

However, Ibbotson had an up-and-down campaign last year and found himself relegated to the WAFL.

He played the first 10 AFL games this season but was axed after the Crows defeat, replaced by mature-age recruit Luke Ryan who has blossomed across half-back.

Ibbotson has played eight WAFL games since and will be a part of the Thunder's finals campaign.

The rangy backman, often asked to fight out of his weight division for Freo, missed out on the Dockers' 2013 Grand Final appearance due to a sore Achilles but is looking forward to helping Peel defend its maiden flag.

"Playing for Peel was always really high on my agenda, especially now that I have qualified for finals," Ibbotson said.

"I missed out last year by one game and watched the boys win the premiership, which was good to see, but it would have been nice to be a part of it.

"I am keen to be a part of it this this year and, hopefully, we have some success."

Ibbotson will leave the Dockers alongside veteran full-back Zac Dawson, who coach Ross Lyon said won't be at the club next season.

Hayden Ballantyne is set for a contract extension, while Freo has decisions to make on uncontracted senior players Michael Johnson, Jonathon Griffin and Nick Suban.

Former rookie Matt Taberner and midfielder Tommy Sheridan are also out of contract at season's end.