The 23-year-old has impressed for Sunderland this season since moving from League of Ireland side Derry City last September.
McClean, who has six goals in 25 appearances for the Black Cats, made his debut for Ireland in the 1-1 draw with the Czech Republic at the Aviva Stadium in February.
Wigan Athletic’s James McCarthy was the surprise exclusion with the 21-year-old withdrawing from selection following the diagnosis of his father with cancer.
The Irish squad will face Bosnia in a pre-tournament friendly on 26 May in Dublin before travelling to Poland in preparation for their first Euro 2012 game against Croatia.
“We will look to emulate the attitude and performance that brought us qualification, and push our limits further as we prepare for this tournament. We will be focused as we enter this important time,” said Trapattoni.
“I had a very difficult task in choosing this 23 man squad. Several players have proven their abilities to us during the qualifying campaign, and we are thankful to all who have played a part.
“However, we are happy with our choices. The standby list consists of very capable players who we would be happy to call upon if needed.
“The game against Bosnia in Aviva stadium will be the beginning of our Euro 2012 journey and it is important for the players to feel the energy from Irish fans before we go to our training camp.”
Republic of Ireland squad for Euro 2012: Shay Given (Aston Villa), Keiren Westwood (Sunderland), David Forde (Millwall); John O’Shea (Sunderland), Stephen Kelly (Fulham), Stephen Ward (Wolves), Richard Dunne (Aston Villa), Sean St Ledger (Leicester), Darren O’Dea (Leeds), Kevin Foley (Wolves); Glenn Whelan (Stoke), Keith Andrews (West Brom), Keith Fahey (Birmingham), Darron Gibson (Everton), Damien Duff (Fulham), Aiden McGeady (Spartak Moscow), Stephen Hunt (Wolves), James McClean (Sunderland); Robbie Keane (LA Galaxy), Kevin Doyle (Wolves), Shane Long, Simon Cox (both West Brom), Jon Walters (Stoke).
Stand-by: Darren Randolph (Motherwell), Paul McShane (Crystal Palace), Paul Green (Unattached), Seamus Coleman (Everton), Andy Keogh (Millwall).
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