The 29-year-old has been struggling with injuries in recent seasons, but impressed in the 2-2 draw at Aston Villa on Sunday.
Hughes said: “We’re starting to see the best of Andy Johnson now. He had a significant injury and he’s been out for a considerable length of time.
“In fairness to him, he’s played a number of games now and his performance levels have been good.
“All that’s been lacking have been goals. Now thankfully he’s added goals. He’s in good shape at the moment.
“He looks strong. He’s completing games at the right intensity and he’s not fading out of games, which you would expect with the length of time that he’s been out.
“He’s been really splendid for the team. Everybody is delighted for him because of what he has been through.”
Hughes added: “Andy has 18 months of his contract left. Do I want to keep him? Yes, absolutely.
“He’s missed a lot of football and we’re hopeful now that he’ll have a run of games and his career will progress without injury.
“He was in the England squad prior to his injury problems. Who’s to say that, if he keeps himself fit, he can’t get himself back into those squads?
“He has recovered so strongly because he is a mentally strong guy.
“He’s had disappointments because he’s come back a little bit too soon because he’s just keen to play.
“I think he’s learned from that and he understands his body now.”