King's last appearance was in the 2009 League Two play-off final
Gillingham's chances of promotion to League One have been boosted by two centre-halves returning from long term injuries in the same week.
Garry Richards, 24, made his first start for nine months in Saturday's 0-0 draw with Oxford after a broken foot.
On Tuesday, Simon King, 27, came on against Rotherham for his first game for 21 months after an ankle injury.
King told BBC Radio Kent: "It was a real special moment, when I went to clap the fans I nearly shed a tear."
He added: "It was like being a kid again making your debut. I wanted to get straight into it, it was always going to be a test for me. I wanted to get that first touch, I started to relax in the second-half and now I want to hold down a place in the team.
"To have a great reception was brilliant. It's been difficult, I've had some real lows, but it's all worth it, all the hours in that gym have paid off."
I have to be careful, the other lads can train every day, but I have to be cautious
Simon King
King picked up the injury in a pre-season friendly at Bromley in the summer of 2009, and has not played a first team game since the 2009 League Two play-off final victory against Shrewsbury.
"It's all part of a learning curve for me," he continued. "The protocol for this week is to stay off it Wednesday and Thursday, a light session Friday and on Saturday see if I'm selected.
"I have to be careful, the other lads can train every day, but I have to be cautious. I just put it down to getting old!"
Although publically King never admitted to any fears that his career was over, he now concedes the thought crossed his mind during the two seasons when he was out of the game.
"It crossed my mind. To be out this long, I thought it was never going to come. But this week has been a very, very, very good week," he said.
There's nothing like playing first team football, you can do all the training in the world, but it's different to get on the pitch
Garry Richards
King's return to the side coincides with team mate Garry Richards, whose appearance in the 0-0 draw with Oxford United was his first start since he broke his foot in a collision with his own keeper Alan Julian in a game against Millwall in April 2010.
Richards said: "It's been a long time, I'd been back in training long enough and have been chomping at the bit to get my first start. There's nothing like playing first team football, you can do all the training in the world, but it's different to get on the pitch."
King and Richards' return comes at a good time for Gillingham as injuries to central defenders mount up. Matt Lawrence went off against Rotherham with a groin injury and both Josh Gowling and Tony Sinclair are still on the sidelines.
Commentary of Crewe v Gillingham on Saturday, 12 February 2011 is on BBC Radio Kent.
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