Barrett's involvement was always doubtful once it became clear that Nehe Milner-Skudder's return to Super Rugby was taking longer than first hoped.
Blues fullback/first five Stephen Perofeta has also been omitted from the 28-man squad as he has yet to return to rugby and it was felt his match fitness would be lacking if he travelled. Peter Umaga-Jensen of the Hurricanes was already ruled out due to a shoulder operation.
Those who missed the cut from the side that swept the Oceania series in Australia last week were props Harrison Allan of Canterbury and Rob Cobb of Auckland, the latter having been injury cover last week, halfback Carlos Price of Wellington and first five Ciarahn Matoe of Taranaki. It still looks a powerful combination, with much versatility in the backline.
Head coach Craig Philpott said it was a difficult task to whittle the squad down to the 28 that will go to Georgia.
"All 32 players we took on the successful Oceania tournament campaign put their hands up for selection, and all merited the opportunity to wear the black jersey in Georgia. We had to make some tough calls and no doubt there will be some disappointed players.
"The squad has a good base of experience with seven players returning from last year's Under 20 World Championship in Manchester. However, we also want to learn the lessons from the last world champs and in particular ensure that we are competitive in the forwards against the big northern hemisphere teams," Philpott said.
"There is a lot to be happy with from our win in the Oceania tournament. We focused on a handful of important aspects of our game, especially defence, and were proud of the fact we conceded only two tries in the tournament.
''With more time together we will hone in on our scrummaging which will no doubt be a decisive area of the games in Georgia. We also want to play our natural high tempo game and provide our backs plenty of space and opportunity to run.
''We scored a lot of tries on the Gold Coast, and our focus now is on ensuring we play with both speed and accuracy.
"We can't afford to lose concentration and our goal is to play world class rugby in every game.''
The team assembles in Mt Maunganui later this week and travels to Georgia on May 24. Their pool matches are against Scotland on May 31, Italy on June 4 and Ireland on June 8.
New Zealand Under 20 squad for World Rugby Under 20 Championship in Georgia:
Forwards: Asafo Aumua (Wellington), JP Sauni (Auckland), Pouri Rakete-Stones (Hawke's Bay), Alex Fidow (Wellington), Ezekiel Lindenmuth (Auckland), Sam Caird (Waikato), Jacob Pierce (Auckland), Isaia Walker-Leawere (Wellington), Sam Slade (Auckland), Luke Jacobson (Waikato, c), Tom Christie (Canterbury), Adrian Choat (Auckland), Marino Mikaele-Tu'u (Hawke's Bay), Dalton Papali'i (Auckland), Ryan Coxon (Waikato), Tim Farrell (Hawke's Bay)
Backs: Kemara Hauiti-Parapara (Wellington), Ere Enari (Canterbury, vc), Tiaan Falcon (Hawke's Bay), Orbyn Leger (Counties Manukau), Thomas Umaga-Jensen (Wellington), Braydon Ennor (Canterbury), Tamati Tua (Northland), Tima Faingaanuuku (Tasman), Caleb Clarke (Auckland), Jona Nareki (Otago), Josh McKay (Canterbury), Will Jordan (Canterbury)