Williams has recovered from a toe injury to be named in the midfield against the Wallabies and will line-up alongside Cardiff Blues centre Owen Williams, who scored on his first outing at the Millennium Stadium last Friday.
Cuthbert will play his first part in this autumn's Test series after successfully recovering from injury. The British and Irish Lions wing has been working closely with the WRU and Cardiff Blues medical teams which has ensured an optimal return.
Cuthbert, who has scored nine tries in his 18 appearances for Wales, will line-up in an experienced back-three with George North (Northampton Saints) and Cardiff Blues' Leigh Halfpenny.
At half back, Dan Biggar (Ospreys) and Mike Phillips (Unattached) continue their partnership which has seen them feature six times together this year.
Gethin Jenkins (Cardiff Blues), who became a centurion on his last outing for Wales a fortnight ago, returns with Richard Hibbard (Ospreys) to the front-row. Rhodri Jones (Scarlets) will start his third consecutive game at tight-head.
British and Irish Lions duo Ian Evans and Alun Wyn Jones (both Ospreys), who started all five of Wales' 2013 RBS 6 Nations games together, renew their partnership in the second-row.
The back-row will line up with Dan Lydiate (Racing Metro) at blindside, alongside captain Sam Warburton (Cardiff Blues) at openside and Toby Faletau (Newport Gwent Dragons) at number eight.
"It's great to have Alex and Scott available and they bring a lot of experience into the backline,” said Gatland.
"Alex and the medical teams have worked really hard to ensure he is ready for this weekend and it's great to be able to bring him back into the side.
"We thought Owen (Williams) performed well in the centre against Tonga and he gets another opportunity on Saturday.
"There is a lot of experience in the pack for what is going to be a very physical game.
"We are looking to finish the series off well, the last three games against Australia have gone right down to the wire and I don't expect anything different this weekend.”
On the bench Scarlets scrum-half Rhodri Williams who made his debut as a second-half replacement against Tonga keeps his place in the match-day squad and is joined by fellow Scarlets backs Rhys Priestland and Liam Williams. Ken Owens (Scarlets), Ryan Bevington (Ospreys) and Samson Lee (Scarlets) are named as the front-row replacements alongside Ospreys duo Justin Tipuric and Ryan Jones, who captained Wales for a record 33rd time last weekend.
WALES TEAM TO PLAY AUSTRALIA
Leigh Halfpenny (Cardiff Blues), Alex Cuthbert (Cardiff Blues), Owen Williams (Cardiff Blues), Scott Williams (Scarlets), George North (Northampton Saints), Dan Biggar (Ospreys), Mike Phillips (Unattached), Gethin Jenkins (Cardiff Blues), Richard Hibbard (Ospreys), Rhodri Jones (Scarlets), Alun Wyn Jones (Ospreys), Ian Evans (Ospreys), Dan Lydiate (Racing Metro), Sam Warburton (Cardiff Blues, CAPT), Toby Faletau (Newport Gwent Dragons).
Replacements: Ken Owens (Scarlets), Ryan Bevington (Ospreys), Samson Lee (Scarlets), Ryan Jones (Ospreys), Justin Tipuric (Ospreys), Rhodri Williams (Scarlets), Rhys Priestland (Scarlets), Liam Williams (Scarlets).
