Earls, who was the second-youngest member of the Lions squad that toured South Africa this time last year, had been hoping to test himself against southern hemisphere giants New Zealand and Australia later this month.
Instead, the 22-year-old centre cum full back will spend the summer at home alongside fellow Lions Paul O'Connell, Stephen Ferris and Luke Fitzgerald.
"Keith Earls has been ruled out of the Ireland squad for the summer tour to New Zealand and Australia," read a statement from the Irish Rugby Union.
"Earls has been suffering from a persistent groin injury and, following his participation in the training camp in Limerick this week, he has been ruled out of the tour."
Like his provincial and Lions team-mate Earls, O'Connell has been affected by groin problems and, despite being named in the original touring party, the 2009 Lions skipper won't be traveling with Ireland.
Leinster and Lions wing Fitzgerald still hasn't recovered from a serious knee injury that required surgery back in November, while Ferris, who had his first Lions tour ended prematurely through injury, is sidelined with a broken cheekbone.
Also absent from the tour party are Leinster flanker Kevin McLaughlin, Ulster hooker Rory Best and Munster No8 Denis Leamy.
McLaughlin picked up a knee injury in the Magners League Grand Final last weekend; Best has an ankle problem, and Leamy is still attempting to regain fitness having been out of action since December.