They open up their Six Nations campaign against Wales.
Offaly's Nichola Fryday will captain Ireland for the first time this weekend.
She's been named in the second row for the Tik Tok Six Nations clash with Wales at the RDS.
Portlaoise's Emma Hooban is among the replacements.
In his first game in charge, McWilliams has opted for an exciting blend of youth and experience in his side having worked closely with the extended squad during a series of preparatory camps at the IRFU High Performance Centre.
Linda Djougang, Neve Jones and Katie O’Dwyer are named to start in the front row, with Sam Monaghan joining newly-appointed captain Fryday in the second row.
Dorothy Wall has returned from injury having missed last Autumn’s November Series to start at blindside flanker, with Edel McMahon selected at openside and Brittany Hogan at number eight.
Reilly, who has featured on the HSBC World Rugby Sevens Series for Ireland, partners Nicole Cronin in the half-backs, with the Limerick native returning to the green jersey to win her 17th Test cap.
There is a new-look centre partnership with Stacey Flood linking up with Eve Higgins in midfield, while Lucy Mulhall, Amee-Leigh Murphy Crowe and Eimear Considine make up an exciting back three.
Haney and McGann are among the replacements tasked with making a big impact, with Hooban, Chloe Pearse and Hannah O’Connor providing the other reinforcements for McWilliams up front. Kathryn Dane, Enya Breen and Beibhinn Parsons complete the 23.
It's a 4:45pm kick-off.
Commenting on his selection, McWilliams said:
"This is a great start for us as a group, we’re really excited about the youth and experience in the team. We’ll learn a lot from this game, but for these players to go out and represent Ireland at the RDS is going to be special. It’ll be a great occasion and I’m excited to see how they perform, because we’ve got through a lot of work over the last couple of weeks."
Third Time The Charm As Laois Claim Joe McDonagh Cup
Offaly Pupils Become Local Stars After Publishing Bestselling Book
Katie Taylor To Fight At Croke Park In September
Laois And Westmeath Set For Big Tests In Intermediate Camogie Championship
I Knew I Had To Play A Good Round To Win - Ella Cantwell
Mullingar Athletic And Clonaslee United To Clash In Combined Counties Cup Final
Shane Lowry And Rory McIlroy In Contention At Memorial Tournament
There's Serious Competition In The Laois Panel - Mark Dowling
Westmeath Ladies Look To Book All-Ireland Quarter-Final Spot
Alex Dunne Aiming For Big Weekend In Monaco
Offaly Camogie Captain Looking Forward To Kilkenny Clash
Shane Lowry In Action At Memorial Tournament
Laois Aiming To Make It Third Time Lucky In Joe McDonagh Cup Decider
Galway To Host Westmeath On Sunday June 14th
Second Round Draw Made For FAI Cup
Cian Reddy Keeps Up Unbeaten Professional Record
Westmeath Ladies Get Opening Win In All-Ireland Intermediate Championship
Athlone Town Knocked Out Of All-Island Cup
Limerick See Off Offaly In Senior Camogie Championship
Athlone Town Suffer Defeat Away To UCD In First Division