Hobbs has pre-agreed a two-year contract at the City Ground if the loan is successful, committing his future to Forest until 2016.
Forest boss Billy Davies has declared himself delighted with the acquisition, claiming that the move is a clear show of strength from Forest ahead of the new Championship campaign.
He told the club's official website: "We are very pleased to welcome Jack to the club.
"He has for some time been recognised as one of the brightest defensive prospects outside the Premier League and I am delighted that we have been able to bring him in.
"Not only do signings like this further signal our intentions this season, but they also highlight the hard work that is going on behind the scenes to ensure we are a force to be reckoned with. Things are slowly falling into place - there is still a lot of work to be done, but Jack is another piece in the jigsaw."
The 24-year-old former Liverpool trainee helped Hull achieve promotion to the Premier League last season, making 22 appearances in the Tigers defence.