The trio all missed the recent drawn series against Afghanistan but will be available for next month’s two ODIs with Pakistan at Malahide, near Dublin.
O’Brien, who struck 72 in Ireland’s 2007 World Cup win over Pakistan, is fit following a calf problem, while Young is back after an elbow injury.
Meanwhile Rankin is set to make his return to Irish cricket, having briefly represented England in just one Test, against Australia at Sydney in 2014.
“It’s great to have an almost full-strength squad to choose from,” said Ireland coach John Bracewell on Thursday.
“The bowling unit performed superbly against Afghanistan with the younger seamers in particular putting their hands up,” the former New Zealand off-spinner added.
“The return of Boyd and Craig adds to that department and gives us plenty of options which is exactly what a coach wants.
“The return of Niall adds experience to the top order. We tried a few different permutations with the batting order last week — some of which worked and some which didn’t.
“Ed Joyce was obviously the stand-out performer in his new role as opener, and it was great to see Gary Wilson return to form.
“It should be a fantastic series — there’s a great recent history between the two countries with some great matches over the past decade, and I’m certain it’ll be two tough games when we meet in Dublin next month.”