The 22-year-old centre-back has joined from Bognor Regis Town for an undisclosed fee.
We spoke to Bognor Regis Town press officer, Carl Eldridge, who has watched Cook on a regular basis, to get some insight into the type of player the Blues have signed...
How would you describe him as a player?
Joe is an accomplished, unflustered central defender who reads the game well. He has great positional awareness and has a dogged determination about his play.
What would you say are his best attributes and what does he need to improve on?
As well as the defensive attributes needed at the back, one of Joe's strengths is bringing the ball out of the back. He's very good on the ball, unusually skilful for a centre-half. Reminds me of Ben White at Arsenal, who can win the ball then stride forward to help launch an attack. I'm told Paul Cook likes to encourage this aspect of play so it will be interesting to see if he continues to flourish in this part of his game. I would think so, and may well be the reason that Chesterfield bought him to the club, to develop this.
Is his best position as a right-sided centre-back? How did he slot in at Bognor?
I think that it's his preferred position and you'd have to say that is where he is naturally suited. With his ball-playing skills, you could see him doing a job as a central defensive midfielder too.
How has he performed at Bognor in his time at the club?
Overall, a stand out player who won his fair share of man-of-the-match awards. He very much suited our style of play, on the front foot and taking the game to the opposition.
Is it a surprise that a club like Chesterfield in a higher league has come in for him?
Not really. Anyone who saw him play at our level could tell he had more to offer and, as our manager Robbie Blake said, it was only a matter of time before he moved up the pyramid.
Do you think he is ready to play in the National League straight away or do you think it might take him a bit of time to adapt?
Thrown straight in, I'm not sure he would let anyone down at the level. But of course he probably needs to come to terms with the physicality in the National League. Like any player moving up a level, time to adapt would be ideal.
What can you tell us about him as a person?
Very polite and always happy to chat to fans -- quite reserved other than that. All in all, a thoroughly nice lad.