Essendon has signed its ninth top-up player for 2016, with former North Melbourne defender Nathan Grima officially joining the club.

After retiring last year following a long struggle with a back injury, the 30-year-old has returned to football and will don the red and black.

The Bombers had hoped to add more height to their list after losing 12 of their players to season-long suspensions in January and Grima will offer an experienced hand in the backline.

"I'm really excited about joining the Essendon Football Club this season, and can't wait to have a second chance at playing AFL," Grima said.

"At first it was my surgeon, John Cunningham, who gave me the confidence that I could get back and play senior football. And after the club's medical staff put me through my paces, I had no doubt in my body or my decision.

"My heart is in this 100 per cent. My wife, family and friends are behind me 100 per cent, and I was never content finishing my career the way I did."

Grima played 86 games for the Roos after being recruited by the Kangaroos as a 22-year-old at the end of 2007.

Essendon list manager Adrian Dodoro said the club "didn't make this decision overnight" and had to be clear Grima's body could withstand another AFL season.

"We know Nathan is a very talented player, but we needed to make sure his body is capable of enduring the physical demands and challenges of an AFL season," Dodoro said.

"He passed an extremely thorough medical, a tough fitness assessment by our strength and conditioning team, and was given the all clear to resume full contact sport by his surgeon."

North Melbourne coach Brad Scott this week admitted he was surprised when Grima contacted the club to inform them of his decision to embark on a return to football.

"It was a real surprise to me. It's a really tough decision for 'Narni' and initially, I've got to be honest, my first thought was concern for his welfare because he's had some pretty significant back injuries over the journey," Scott told SEN.

"At the end of last year our discussion was mostly around his well-being in life, not just in sport. I wanted to make sure he was in the best medical hands to live a fulfilling life, and to be able to pick up his kids when that day comes.

"It was a surprise to me that we'd gone from that conversation to him playing again."