Cattermole was handed few opportunities under Dick Advocaat over the early part of the campaign, but he has been immediately reinstated under Sam Allardyce.
And Merson feels that Allardyce has made a good choice by putting the combative central midfielder back into the Black Cats' line-up.
"I know he was kept out of the team by Dick Advocaat, but if I was manager of Sunderland he'd be the first name on the team sheet," he said.
"I know sometimes he shoots himself in the foot, and he's his own worst enemy, but you have to have that fight. He is one of those players who will always look for the ball, no matter how badly he's playing."
Cattermole was short of form, like many members of the Sunderland squad, over the first few matches of the new season.
However, his performance against Newcastle United suggested that he is close to returning to his best, and that could be crucial for the side.
Sunderland beat their near neighbours 3-0 on Sunday, with Cattermole showing all of his best qualities as he dominated the midfield battle alongside Yann M'Vila.
Cattermole will be hoping that his performance against the Magpies can kick-start his season, as getting him back to form will be crucial to Sunderland's chances of preserving their Premier League status.