Having not featured for Bolton since March 2008, Hunt is enjoying the opportunity to play regular first-team football with the Rams.
"I've really enjoyed myself at Derby and I'm pleased to be staying longer," the 26-year-old told the club's official website.
"I just love playing football. I've not played too much over the last year or so and coming here has been a new lease of life for me.
"I'm grateful to Nigel Clough and Derby County for giving me this opportunity and I'm just looking to repay their faith with performances on the pitch."
Rams boss Clough, who is also keen to keep DJ Campbell and Lee Johnson, is happy to have been able to extend Hunt's loan.
Clough said: "Nicky has been tremendous for us so far and we're delighted he is staying on.
"With the more games he plays he will only get better."
Coca Cola Ch'ship Promotion 09/10 Win Outright: Derby 66/1