Adams missed the 38-23 defeat of Fiji last weekend due to a calf injury, but the winger will face the Wallabies.
Uilisi Halaholo and Nick Tompkins are Wayne Pivac's centre pairing, while the fit-again Aaron Wainwright is back at number eight.
Wyn Jones and Tomas Francis return to the starting line-up for what will be the final Test of the year for both sides.
Samu comes into the Australia team in the absence of Hooper, who suffered a foot injury in the loss to England at Twickenham last Saturday.
Props Taniela Tupou and Allan Alaalatoa return after missing the defeat to the Red Rose due to concussion, while Tolu Latu starts at hooker and Filipo Daugunu gets the nod on the wing alongside Andrew Kellaway.
Centre Lalakai Foketi is set to make his debut off the bench, with James Slipper taking over as skipper.
Wales team: Liam Williams, Louis Rees-Zammit, Nick Tompkins, Uilisi Halaholo, Josh Adams, Dan Biggar, Tomos Williams; Wyn Jones, Ryan Elias, Tomas Francis, Adam Beard, Seb Davies, Ellis Jenkins (captain), Taine Basham, Aaron Wainwright.
Replacements: Elliot Dee, Gareth Thomas, Dillon Lewis, Ben Carter, Christ Tshiunza, Gareth Davies, Rhys Priestland, Johnny McNicholl.
Australia team: Kurtley Beale, Andrew Kellaway, Len Ikitau, Hunter Paisami, Filipo Daugunu, James O'Connor, Nic White; James Slipper (captain), Tolu Latu, Taniela Tupou, Rory Arnold, Izack Rodda, Rob Leota, Pete Samu, Rob Valetini.
Replacements: Folau Fainga'a, Angus Bell, Allan Alaalatoa, Will Skelton, Lachlan Swinton, Tate McDermott, Lalakai Foketi, Tom Wright.