The Lions trio will join Daniel Merrett, Jed Adcock and skipper Jonathan Brown as the club's official leaders.
Former captains Luke Power and Simon Black will step back from the leadership group to play a mentoring role with the Lions' younger players.
Lions coach Michael Voss said the appointments were made with an eye to the long-term future.
"As a group, we have spent a lot of time and energy ensuring the promotion and development of the next crop of leaders at the club," Voss said.
"It was important for the team that we did that. This is about the next generation of Brisbane Lions taking ownership of the team and we've seen some terrific signs of that during the pre-season."
Rockliff is the youngest of the leadership group at just 21 years of age and with 20 games to his name.
But Voss said he had shown he was worthy of the honour.
"Tom Rockliff, while one of the younger guys in the group, constantly displays outstanding leadership among the group and to make him officially part of the leadership group was a fairly straightforward decision for us," Voss said.
"Likewise, Mitch Clark is entering his sixth season here at the Lions and over that time, has established himself as one of the leaders of the group.
"Josh Drummond, at 27, has long served in a mentoring role to the younger guys who have come through, and we felt that he was deserving of that official recognition of being elevated to the leadership group."
Mitch Clark is a $313,400 ruck in the Toyota AFL Dream Team competition
