It is part of the celebration planned on the day to commemorate the 130th anniversary of the Welsh Rugby Union as the game's governing body in Wales.
The choir will assemble in the north stand of the stadium where they will be conducted by the stadium's feature choirmaster, Haydn James.
He has devised a special repertoire of song for the day which along with the favourite hymns of old will include some modern tunes as well.
The choir will also unveil a medley of songs which Haydn James is preparing to honour the countries represented by the players in the Barbarian line up.
Fans will be able to hear the massed choir from 1.30pm which is precisely one hour before the kick off.
The songs will be part of the celebratory build up to the game which will also feature entertainment and films yet to be announced.
Supporters will be encouraged to join in the singing to ensure the capital city echoes to the sound which will boom out across Cardiff.
The massed choir will also strike up during the match to raise the noise level to a massive intensity as the game unfolds.
Some of the favourite hymns and songs to be sung will include Gwahoddiad, Llef, Llanfair, Rachie, Speed Your Journey and Myfanwy.
The choir will be accompanied by the Regimental Band of the Royal Welsh which regularly features at Wales home international matches.
Haydn James said: "This should give a spectacular sound from some of the very best choirs in Wales.
"We are all absolutely thrilled that so many choirs will be sharing in this very special day."
The massed choir will congregate in the north stand of the stadium to ensure a coordinated sound of song is created on the day.
The full list of choirs recruited so far is:-
Llanelli Male Voice Choir, Dunvant Male Choir, Morriston Orpheus Choir, Cardiff Arms Park Male Choir, Cor Meibion Taf, Pendyrus Male Choir, Bechgyn Bro Taf, Treorchy Male Choir, Cor Meibion De Cymru, Froncysyllte Male Choir, Cor Dodre'r Aran, Cor Meibion Llangwm, Cantorion Colin Jones, Built Wells Male Choir, Cor Meibion Maesteg, Maesteg Gleemen, Cor Yr Hen Blwyf, Glynneath Male Choir, Cor y Gyrlais, Eschoir, Cor Meibion Dyffryn Aman and Risca Male Choir.
The Millennium Stadium Manager, Gerry Toms, said: "The stadium is known for its singing but this choir will make the sound extra special on the day.
"The acoustics in the bowl of the stadium are fantastic for capturing the noise of the supporters and the sound made by this excellent line up will make the hairs on the backs of people's necks stand up.
"We have had large choirs here in the past and anyone who has experienced those occasions will know how spectacular it can be.
"The music will start an hour before kick off so we are encouraging supporters to arrive early so they don't miss out.
"The Wales v Barbarians match has been arranged to mark the 130th anniversary of the WRU so we want to make it a day to remember for everyone involved.
"I know the players always appreciate the singing so we can expect some inspired action on the field when the whistle goes."
More details of the pre match events for the Wales v Barbarians international will be announced shortly by the WRU.
Tickets are available priced at £40 and £30 for adults and £100 for a family ticket (2 adults 2 children) and there has also been a new pricing category introduced this season which offers £15 tickets for the under 18s enclosure.
Tickets can be purchased online at www.wru.co.uk/tickets or by calling the ticket hotline 08442 777 888 or Ticketline on 02920 230130.