Cousins was left out of the side last week after experiencing some soreness in his knee but trained well this week, earning himself a place in the Tiger's 22.
"He's a definite starter," Hardwick said at Punt Road on Friday morning.
"He's trained really well this week which has been pleasing so he'll play and hopefully he plays well for us. He's an important player to our side and just adds a lot of experience and knows how to play the game and our young guys can learn a lot off him."
While Hardwick is looking forward to seeing the 31-year-old have an impact with the ball, it's his leadership on the field that the coach believes is his greatest asset to the young list.
"Probably the greatest thing he gives is his on-field leadership. The thing with a young group is that they're always thinking about themselves and how they get themselves in the game," Hardwick said.
"What Cuz does is actually provide great leadership on the field for us and that's really important for our young player's careers."
Cousins is one of six changes the Tigers made for round three, with Alex Rance, Shane Tuck, Dean Polo and Matthew White all playing their first games this season.
"We're looking to give some others a chance," Hardwick said.
"A guy like Alex Rance has played well in the reserves as have Tuck and Polo. Some of the guys that went out were probably a little bit stiff but we thought we could get some more input from the guys coming in."
Ball-winner Shane Tuck returns to the senior side for the first time in 2010 after the coaching staff worked with him in the off-season to adjust his role in the side.
"We feel with our midfield with Cotchin, Deledio and Martin, that we needed to reconfigure Tucky in a way. So you'll see him playing a different role, which he's excited about and I'm excited about too," Hardwick said.
"It's good to have him back in the side ... he's a competitive man and that's what I like about him, so hopefully he comes in this week and has a good game."
Mature-age recruit Relton Roberts has also been given a chance to prove himself after missing Round 2 for disciplinary reasons.
"We felt he deserved another chance to show us what he's got. We think he's going to be a player for our future so we want to give him every opportunity to show us how he can play."
Will Thursfield (leg) and Mitch Farmer (leg) will be sidelined this week due to injury, while small forward Robin Nahas, Jake King, Tom Hislop and Adam Thomson have been dropped.
