In the forwards hooker Dylan Tierney-Martin and second-row Charlie Ryan both featured last season, as did out-half Harry Byrne and wingers Angus Kernohan and James McCarthy.
Clontarf's David Hawkshaw is named as captain, with Ryan and scrum-half Craig Casey named as vice-captains.
The side will play their two home games against England and France in Irish Independent Park.
On selection of the squad, McNamara said: "It's always an exciting time when the Six Nations comes around and things have been building well since before Christmas. We had two good run outs against Leinster and Munster Development sides where the players had the opportunity to put their hands up for selection for this squad.
There's a lot of talent in the playing group, and we're looking forward to seeing these young men run out in the green jersey over the coming weeks.
We also have a new home this season in Irish Independent Park, which is a great venue and I'm sure there will be a superb atmosphere when we welcome England and France under lights on Friday evenings."
Commenting on the squad announcement, David McGee, Markets & Strategy Partner at PwC Ireland said:
"At PwC, we are excited to kick-off this year's Six Nations Championship as we enter our fourteenth year as sponsors of the Ireland U20 squad.
We are proud to support such a hard-working team. They embody our aim as a firm to think beyond the now and build a platform for the future.
As the progression from the U20s to the full senior squad becomes more pronounced, we look forward to following the development of these players throughout this campaign.
We take pride in our focus on developing talent to ensure the best results for our people, our clients and our business partners. We know that Irish Rugby shares the same approach.
Finally, I would like to wish the team the very best of luck in the upcoming Championship. I have no doubt they will do us proud."
Ireland will get their campaign underway against England on Friday week in Irish Independent Park at 7.15pm and their second fixtures sees them travel to Netherdale outside Edinburgh to take on Scotland.
They are on the road again for their third fixture against Italy in Rieti, before facing France back in Irish Independent Park.
Their final game of the tournament is away to Wales on the 15th March in Colwyn Bay.
Tickets for the home fixtures in Irish Independent Park are available from www.ticketmaster.ie
IRELAND U20 Squad, sponsored by PwC, for the U20 Six Nations Championship 2019
Forwards:
Azur Allison (Ballymena RFC/Ulster)
Ryan Baird (Dublin University FC/Leinster)
Tom Clarkson (Dublin University FC/Leinster)
Giuseppe Coyne (Dublin University FC/Leinster)
Brian Deeney (Clontarf FC/Leinster)
John Hodnett (UCC RFC/Munster)
Paddy Kelly (Young Munster RFC/Munster)
Ryan Lomas (Galwegians RFC/Connacht)
Luke Masters (Shannon RFC/Munster)
David McCann (Banbridge RFC/Ulster)
JJ McKee (Ballymena RFC/Ulster)
John McKee (Old Belvedere RFC/Leinster)
Michael Milne (UCD RFC/Leinster)
Martin Moloney (Old Belvedere RFC/Leinster)
Niall Murray (Buccaneers RFC/Connacht)
Scott Penny (UCD RFC/Leinster)
Charlie Ryan (UCD RFC/Leinster) * Vice-Captain
Billy Scannell (Young Munster RFC/Munster)
Dylan Tierney-Martin (Corinthians RFC/Connacht) *
Ronan Watters (St. Mary's College RFC/Leinster)
Josh Wycherley (Young Munster RFC/Munster)
Backs:
Harry Byrne (Lansdowne FC/Leinster) *
Craig Casey (Shannon RFC/Munster) Vice-Captain
Jake Flannery (Shannon RFC/Munster)
Sean French (Cork Constitution RFC/Munster)
Cormac Foley (St. Mary's College RFC/Leinster)
David Hawkshaw (Clontarf FC/Old Belvedere) Captain
Ben Healy (Garryowen RFC/Munster)
Bruce Houston (Ballymena RFC/Ulster)
Iwan Hughes (Ballynahinch RFC/Ulster)
Angus Kernohan (Queen's University RFC / Ulster) *
James McCarthy (UL Bohemian RFC/Munster) *
Stewart Moore (Malone RFC/Ulster)
Oli Morris (Saracens / IQ Rugby)
Aaron O'Sullivan (UCD RFC/Leinster/IQ Rugby)
Conor Phillips (Young Munster RFC/Munster)
Colm Reilly (Buccaneers RFC/Connacht)
Rob Russell (Dublin University FC/Leinster)
Liam Turner (Dublin University FC/Leinster)
Jonathan Wren (Cork Constitution FC/Munster)
*Denotes Previously Capped at U20 level
IRELAND U20 Six Nations Fixtures 2019
Friday 1st February 2019
Ireland U20 v England U20, 7.15pm, Irish Independent Park, Cork
Live on RTE
Friday 8th February 2019
Scotland U20 v Ireland U20, 7.30pm. Netherdale, Galashiels
TBC
Friday 22nd February 2019
Italy U20 v Ireland U20, Stadio Centro d'Italia, Rieti
Stream via FIR - Facebook.com/Federugby & Youtube.com/Fedrugby
Friday 8th March 2019
Ireland U20 v France U20, 7.15pm, Irish Independent Park, Cork
Live on RTE
Friday 15th March 2019
Wales U20 v Ireland U20, 7.15pm, Stadwim Zip World (Parc Eirias), Colwyn Bay
Live on RTE
