The family had come to New Zealand on business.
Post-mortem examinations were being carried out on the woman and child this morning.
Police spokeswoman Noreen Hegarty said investigators were not seeking anyone else in relation to the deaths.
It was expected the case would be referred to the coroner.
Late last night, police were still at the site where the bodies were lying, near the complex's pool area.
'It was an ugly sight'
One couple said they saw a woman with a baby in a highly distressed state in the lobby about half an hour before the deaths.
The woman was yelling into a cellphone.
"She wasn't speaking English," one said. "She was just crazy, definitely distressed ... The baby was wrapped in a blanket. They were sitting in the lobby. The baby wasn't crying."
Just before 5.30pm, another resident, Saj Din, heard what sounded like an explosion as he watched television in his 12th-floor apartment.
He heard sirens and looked out of his window.
"There were a couple of bodies. The deck around the pool was smashed up.
"It was an ugly sight. I knew they were gone."
Residents said the pair fell from the 26th floor onto the elevated pool area.
A resident of a fourth-floor apartment said he arrived home about 5.45pm to find dozens of police cars, and the building in "complete lockdown". It was 6.30pm before he was allowed back up to his room.
Support offered to St John response staff
St John district operations manager John Takerei said an advanced life support ambulance crew and team manager were sent to the scene.
Support was being provided to the St John staff, because of the "traumatic nature" of the incident.
According to its website the Auckland Harbour Oaks building is 37 storeys high - the tallest in the country - and contains rental apartments and hotel rooms.
