Danny Fox, Anthony Pilkington, Lewis Macleod, Gary Roberts and Michael Jacobs – all out of contract on June 30 – have agreed extensions until the revised end of the season on July 22.
Loan trio Kieran Dowell, Alex Dobre and Leon Balogun will also stay for the last eight games, while Joe Garner has signed a new one-year deal.
Talks remain ongoing with Chey Dunkley and Brighton loan forward Jan Mlakar, with on-loan Chelsea defender Dujon Sterling the only player who will not be staying on.
“I’m delighted to get them all done,” gushed Cook.
“The squad has been excellent for a long period of time now.
“I think leading up to the transfer window in January, it was a little bit ‘iffy’.
“Obviously with a few lads coming into the last transfer window before their contracts end, maybe one or two lads being a little bit unsettled at the club.
“As a manager, that harmony in the dressing is absolutely crucial.
“You look at the senior players…Pilkington, Fox, Garner, Roberts…those types of lads have been excellent at the club.
“For them to extend, and the loans to also re-sign, helps that harmony which will play a massive part in the last eight games.”
Several other clubs have seen out-of-contract players refusing to play in the run-in for fear of getting injured.
And Cook admits that was freely discussed in all the negotiations.
“Leading into the talks, I actually said to the players: If you’re not going to be committed, don’t sign!'” he revealed.
“And that’s the crucial truth of the situation.
“Having committed players for the run-in is absolutely paramount.
“Having non-committed players is no good for anyone.
“And I fully understand why any of them would not have wanted to sign an extension, because they’re worried they might get injured…I’m on their side.
“Thankfully we’ve had all those conversations, and we can now concentrate on the football.”