Mason has joined Championship rivals Wolves on a three-and-a-half-year deal for an undisclosed fee.
Hudson played alongside Mason, who scored 22 goals in 60 league starts since joining Cardiff from Plymouth in 2011
"I wouldn't want to see him leave my squad," Huddersfield's Hudson said.
Former Republic of Ireland Under-21 forward Mason had been a target for Wolves in the summer.
"For me it's a strange one why they would need to sell to a rival club, especially another team looking to push into the play-offs," Hudson added.
"I think he's a great player, his movement and the way he ghosts in and out of games. He always hits the target when he gets a chance.
"If he's playing week in, week out I think he's probably going to be one of the top-scorers in the league."
Wolves' Wales midfielder Dave Edwards, who will be out for 12 weeks after having surgery on a foot injury, says Mason would be a "much needed addition" to the squad.
"We're a bit low on numbers at the moment, especially in the forward areas," Edwards told BBC Wales Sport.
"I've always been impressed every time I've seen him.
"I thought he played very well at Molineux a few weeks ago when we were beaten 3-1 [by Cardiff].
"He works hard for the team and hasn't got a bad goalscoring record either. He'll be great for us."
Former Cardiff City captain Mark Hudson does not understand why striker Joe Mason has been sold to Wolves.