The former striker feels the 33-year-old will have a big influence on the Bluebirds and says that his experience and quality can help the Welsh side adapt to the top flight
The Welsh club will be making their first appearance in the Premier League after having won the Championship, finishing eight points clear of Hull City.
Hartson says the 33-year-old’s experience will prove vital and may help the younger members of the squad adapt to life in the top flight.
"He will be massive for Malky Mackay next season,” he told BBC Sport. "Craig's got great experience of the Premier League. He's got real quality
"He will be able to help those young players who have never played at this level before. Craig's obviously had a wonderful career at West Ham, City and Liverpool. He's vastly experienced.”
Hartson also warned that Bellamy’s age and injury record mean he will need handling carefully so that he can feature regularly for Cardiff.
"I'm sure Craig will want to play every week - I know what the boy is like. But I think Malky will have to put the reins on him at times and hold him back slightly,” he added.
"He's the other side of 33 now and you wouldn't expect him to play every single game, but he's in great condition and looks after himself."
The former striker is also expecting some transfer activity from the Bluebirds as they seek to bolster the squad ahead of the new campaign.
"No doubt Malky will look to bring in three or four new players, maybe a little bit of experience," Hartson added.
"But I think Malky's the type of manager to go and say to his players 'we'll give you an opportunity in the Premier League'.
"You don't know if you can perform there and if that's your level until you're actually thrown in and you go and prove yourself.
"I think we will have a bit of respect for the boys that brought them up."