Kearney has overcome a groin problem to replace Geordan Murphy in the team that beat the United States 22-10 on Sunday, while O'Brien takes over from Shane Jennings after recovering from a knee issue.
Healy, who flew out late to New Zealand because of an eye injury, starts in place of Tom Court, who drops to the bench.
Irish head coach Declan Kidney also recalled first-choice scrumhalf Eoin Reddan with Conor Murray dropping to the replacements bench.
The team will again be led by captain Brian O'Driscoll, one of nine players in the starting lineup from Leinster, who won the Heineken Cup last season.
Australia lead Pool C after their bonus point victory over Italy on Sunday with Ireland one back on four points. Russia, who are yet to play a match, are the other side in Pool C.
Team: 15-Rob Kearney, 14-Tommy Bowe, 13-Brian O'Driscoll, 12-Gordon D'Arcy, 11-Keith Earls, 10-Jonathan Sexton, 9-Eoin Reddan, 8-Jamie Heaslip, 7-Sean O'Brien, 6-Stephen Ferris, 5-Paul O'Connell, 4-Donncha O'Callaghan, 3-Mike Ross, 2-Rory Best, 1-Cian Healy.
Replacements 16-Jerry Flannery, 17-Tom Court, 18-Donnacha Ryan, 19-Denis Leamy, 20-Conor Murray, 21-Ronan O'Gara, 22-Andrew Trimble.