Head coach Rennie, who replaced Michael Cheika after last year's Rugby World Cup but began work in June, named a youthful first squad earlier this month - including 16 uncapped players, eight of whom debuted in Super Rugby this season.
However, there was still room for six-year Wallabies skipper Hooper, although no captain was initially indicated in the selection.
Rennie had previously said no decision had yet been made on the identity of his on-field leader, but he announced a "straightforward decision".
"I've been really impressed with Hoops," Rennie said. "We've spoken a lot over the past nine months and it's highlighted his passion and commitment.
"He's a good man with an outstanding work ethic and he's a great role model for our young men coming through.
"He's keen to lead and is highly respected by the Wallaby family. In the end, his appointment was a straightforward decision."
Hooper said: "It's an absolute honour to be the Wallabies captain and I want to thank Dave and the Wallabies management team, as well as Rugby Australia, for their support and endorsement.
"It's a privilege to wear the Wallabies jersey, I feel proud to lead my team-mates and to represent those players that have before and all Australians.
"I'm really excited about this group and the direction we are heading. We have already spent some quality time together, defining who we are and what we stand for and what we plan to achieve in the coming months."