The Algerian midfielder spent time on loan at the City Ground last season and is set to make a permanent move to become new manager Sean O'Driscoll's first signing after he passes a medical.
"When I heard that Adiene was available for transfer, I moved quickly to sign him," he told the club's official website.
"He knows the club, knows the fans, and knows what's expected of him on the field. I look forward to utilising his expansive midfield play this season."
Forest's new owners, the Al Hasawi family, also released a statement confirming the signing of Guedioura.
"The Al Hasawi family is delighted to have secured Adiene Guedioura as Nottingham Forest's first signing under our ownership," said chairman Omar Al Hasawi.
"He made a huge impact on the team last year and is just the kind of exciting player that we want to see gracing the City Ground this season."