Berahino has seen his career stagnate at The Hawthorns under Tony Pulis, having not featured at all in the first-team squad since October, and he departed the West Midlands with some strong words from his former manager.
Hughes is now hoping to get his new forward back up to speed following his stint in a French fitness camp earlier in the season, but is unsure when he will be integrated into the starting lineup.
"We are delighted with [the signing]," he told reporters. "The platform we will give him will allow him to get back on track. He's obviously stalled for the last 18 months, but he's an outstanding player.
"We know where he needs to be in terms of fitness, but we will turn that around. He isn't going to start games anytime soon, but he can have an impact. He's not unfit, but he's not match fit.
"He plays off the shoulder and more often than not if he gets chances he will take them. We think we will get him back on track and he will be a good player for a long time."
Berahino scored 23 league goals in 105 appearances for the Baggies