The 35-year-old captain, who has scored 67 goals in 143 appearances for his country, was a doubt for the squad after picking up a calf injury last weekend.
Ireland begin their campaign against Sweden on June 13 before also taking on Belgium and Italy in Group E.
Ireland squad for Euro 2016:
Goalkeepers: Shay Given (Stoke City), Darren Randolph (West Ham United), Keiren Westwood (Sheffield Wednesday)
Defenders: Cyrus Christie (Derby County), Seamus Coleman (Everton), Richard Keogh (Derby County), Shane Duffy (Blackburn Rovers), John O'Shea (Sunderland), Ciaran Clark (Aston Villa), Stephen Ward (Burnley), Robbie Brady (Norwich City)
Midfielders: Aiden McGeady (Everton), David Meyler (Hull City), Jeff Hendrick (Derby County), Stephen Quinn (Reading), James McCarthy (Everton), Glenn Whelan (Stoke City), Jonathan Walters (Stoke City), Wes Hoolahan (Norwich City), James McClean (West Bromwich Albion)
Forwards: Daryl Murphy (Ipswich Town), Shane Long (Southampton), Robbie Keane (LA Galaxy)