Ireland ended a 111-year drought spanning 29 tests against the All Blacks with a superb 40-29 win in Chicago and face the world champions again next week before rounding off their November test series against Australia.
The injury-prone O'Brien lasted 20 minutes of this year's Six Nations before a hamstring injury ended his campaign while fellow flanker O'Mahony has not played for Ireland since a knee injury suffered at the 2015 World Cup put him out for a year.
The exciting 21-year-old Leinster centre Ringrose is one of three new caps to start alongside Munster's Jack O'Donoghue and Billy Holland. James Tracy, John Ryan, Dan Leavy, and Niyi Adeolokun could also win their first caps off the bench.
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"He was really close to playing last week obviously and he's given us confidence that he's ready," Schmidt said of Ringrose, who was an unused substitute against New Zealand.
"I think Garry's a really natural player, he sees things and he's already ahead of the game because he reads the game early. It allows him to just avoid those full contacts and slip by players and at the same time being so astute defensively."
Team: 15-Tiernan O'Halloran, 14-Craig Gilroy, 13-Garry Ringrose, 12-Luke Marshall, 11-Keith Earls, 10-Paddy Jackson, 9-Kieran Marmion; 8-Jack O'Donoghue, 7-Sean O'Brien, 6-Peter O'Mahony, 5-Billy Holland, 4-Ultan Dillane, 3-Finlay Bealham, 2-Sean Cronin, 1-Cian Healy.
Replacements: 16-James Tracy, 17-David Kilcoyne, 18-John Ryan, 19-Donnacha Ryan, 20-Dan Leavy, 21-Luke McGrath, 22-Joey Carbery, 23-Niyi Adeolokun.
(Reporting by Padraic Halpin, editing by Pritha Sarkar)
