Winger Josh Adams, hooker Elliot Dee, No.8 Taulupe Faletau, lock Dafydd Jenkins, centre Joe Roberts and fullback Liam Williams are all back in the squad after injury, though Gatland has something of a crisis at five-eighth.
With Gareth Anscombe out of favour and Sam Costelow injured, Ospreys five-eighth Dan Edwards is one of two uncapped players selected, along with Scarlets winger Ellis Mee.
Ben Thomas, who plays predominantly as a centre, is the other No. 10 option.
There were also recalls for tighthead prop WillGriff John and hooker Sam Parry.
Flanker Morgan leads the team with Dewi Lake injured.
Wales begin their campaign in Paris against France on January 31.
"We've selected a squad that we feel has a good blend of exciting young talent and experience," Gatland said.
"This group of players has a huge amount of potential and we will be working incredibly hard together this campaign.
"Every single training session is incredibly important in terms of our preparation for that first game and I'll be looking to see a lot of hard work and everyone working together."
Gatland has discarded young fullback Cameron Winnett despite him featuring in every squad in 2024. Taine Plumtree, Rio Dyer and Max Llewellyn also miss out.
WALES SIX NATIONS SQUAD:Â
Forwards: Keiron Assiratti, James Botham, Elliot Dee, Taulupe Faletau, Dafydd Jenkins, WillGriff John, Evan Lloyd, Kemsley Mathias, Jac Morgan (capt), Sam Parry, Tommy Reffell, Will Rowlands, Nicky Smith, Gareth Thomas, Freddie Thomas, Henry Thomas, Christ Tshiunza, Aaron Wainwright, Teddy Williams
Backs: Josh Adams, Ellis Bevan, Dan Edwards, Josh Hathaway, Eddie James, Ellis Mee, Blair Murray, Joe Roberts, Tom Rogers, Ben Thomas, Nick Tompkins, Owen Watkin, Liam Williams, Rhodri Williams, Tomos Williams
