Tonali was banned by the Italian Football Federation in October for breaching rules while playing in Serie A and has been sorely missed by Newcastle fans.
The 23-year-old's ban expires today, meaning he is eligible to play for the Magpies against Forest in the Carabao Cup tomorrow.
"He will definitely be in the squad," said Howe. "He is fit, he just hasn't had the match (practice) - the most important thing with the game time.
"He has done everything else - he has worked incredibly hard to be on top of his fitness."
The Italian is the Magpies' second most expensive signing and has only made 12 appearances for the club. Howe explained how the midfielder must be feeling.
"When you have a long time out, you have a long time to analyse and reflect. Now it is just back to doing what he loves. It will be an incredible release for him.
"The microscope is on everybody and it will be on him for a period of time. He understands that and we understand that. It is just about small steps.
"He has to play to his strengths and not do anything too out of the ordinary."