WEST Coast midfielder and Hawthorn champion Sam Mitchell will reportedly retire at the end of the season, ending one of the game's most decorated careers.

The author of Mitchell's looming biography, Glenn McFarlane, wrote on Friday morning that the 34-year-old would soon announce his retirement, effective at the end of the season.

The four-time premiership Hawk and 2012 Brownlow medallist has long held plans to move into an assistant coaching role with the Eagles after crossing to the club for the 2017 season.

Last week, Mitchell had a taste of life in the coach's box when he was rested for West Coast's loss to Collingwood. 

Mitchell played 307 games with the Hawks between 2002-16, winning five club champion awards, including the 2016 Peter Crimmins Medal in his final season with the club. 

His bombshell trade to West Coast at the end of last season was one of the most unexpected in the game's history, coming after coach Alastair Clarkson put forward the suggestion of Mitchell joining the Eagles.

"You could have knocked me over with a feather," Mitchell said at the time, before deciding a move was the right decision for his young family.

Regarded as one of the game's greatest ever players, Mitchell was recruited with pick No.36 in the 2001 national draft.

The 180cm midfielder won the 2003 NAB AFL Rising Star award in his second season, proving critics who said he didn't have the physical attributes to excel in the game wrong.  

From there he went on to become one of the most decorated players in the game's history.

He was awarded the 2012 Brownlow Medal last year, alongside Richmond captain Trent Cotchin, after Essendon midfielder Jobe Watson handed back the medal.

He captained the Hawks to the 2008 flag and was a vital contributor to the premiership three-peat of 2013-15, with his ability to extract the ball at stoppages and distribute or organise the team from half-back.

The champion onballer's CV also includes a third placing in the 2015 Brownlow Medal and top three placings in four club champion awards, outside the five he has won (2006, 2009, 2011, 2012, 2016). 

Mitchell holds an equal share with Gold Coast superstar Gary Ablett for the most Brownlow Medal votes in the history of the game (220) under the 3-2-1 system.

Mitchell, who has played 15 games and averaged 27 possessions this season, returns to the Eagles' team to face the Brisbane Lions on Sunday.


Sam Mitchell spent time in the West Coast coach's box in last week's loss to Collingwood. Picture: AFL Photos