Essendon defender James Kelly has announced his retirement, with the former Cats great telling teammates of his decision on Wednesday morning.

The three-time premiership player and key member of Geelong's brilliant era joined the Bombers on the eve of the 2016 season as a additonal player after the club lost the 12 senior players on the eve of the season.

He played 20 games and finished runner-up in the best and fairest, and has played 17 games this season, including his 300th AFL game.

"I feel really fortunate that I've been able to come this far in my career and play for two really great clubs, and have a lot of success at one. I'm eternally grateful I've been able to experience the highs and lows of footy and be a part of two really unique groups," Kelly said on Wednesday.

"I finished my career at Geelong and I was pretty worn out and tired, and I came here and the Essendon Football Club reignited my passion for the game."

Kelly, who will explore a career in coaching next year, said he had known for some time this season would probably be his last at the top level.

"I was probably 50-50 [about going on another year] and I think the club was probably 50-50 as well. I really felt it wasn't the best thing for the club for me to keep playing," he said.

"I'm sure I could have, and we genuinely got there mutually. I felt like if the club wanted me to and needed me to play, I certainly could, but at the end of the day if I finished my career with 330 games or 310, that does nothing f0r the footy club.

"The best thing is to finish now and hand it over to other guys who need the opportunity to play and be good players."

Kelly arrived at Essendon, having retired at the end of 2015 from the Cats, with the aim of helping the strife-torn club, reeling from the year-long bans to 34 past and present players.

He said he was glad he had taken the call from the Bombers and resurrected his career, and that he believed he had been able to make a difference in his two seasons.

"I was a little bit unsure [at the start]. But pretty quickly into it I was really happy I had come back into footy," he said.

Coach John Worsfold said the club would need to look at its coaching structure for next season before offering Kelly a position on the panel, but that the timing of the decision meant Kelly could pursue a spot around the competition.

"It was getting to that point where James needed to know if he wanted to pursue a coaching career or opportunities, he could start to look at that now rather than post-season," Worsfold said.

Kelly, who turns 34 later this year, will play out the rest of the season, with his announcement following Jobe Watson's confirmation that 2017 will also be his last year in the red and black.

Kelly will line up against the Gold Coast on Saturday night, as Essendon heads into the final two rounds of the season needing to win both games to claim a top-eight position.

Ruckman Tom Bellchambers is expected to play against the Suns after missing last week's loss to Adelaide with a foot concern, with Matthew Leuenberger appearing unlikely as he battles an achilles problem.