Earlier, Obama met with Prime Minister Jacinda Ardern after being welcomed at Government House with a stirring powhiri.
Obama's first words to Ardern were about her pregnancy - as they walked off for a meeting together, the former President was heard saying "so, I hear you are expecting."
Obama arrived back in Auckland after two days golfing in Northland with former PM Sir John Key this afternoon.
He arrived at Government House around 3.50pm - an event which potentially was the only chance for members of the public to catch a glimpse of the former President.
The pōwhiri was led by iwi Ngāti Whātua o Ōrākei.
Chief executive Rangimarie Hunia told Newstalk ZB it was an "absolute honour" for the iwi.
"We see him as one of the most influential leaders on the planet. To have the opportunity to welcome him in our traditional language, through the eyes and heart of our culture, means a lot to our people.
"We hope we can do the nation proud."
Obama then met with Prime Minister Jacinda Ardern, who was remaining quiet about what she planned to discuss.
Tonight's main event will be a dinner and discussion with actor Sam Neill in front of 800–1000 guests at the Viaduct Events Centre.
That meal has been chosen and overseen by chef Peter Gordon, who was flown from London by Air NZ for the occasion.
Gordon told 1 News he was told Obama liked fish so had selected New Zealand salmon as one option and steak for the other "because he's from Chicago".
The MC for the event will be poet laureate Selina Tusitala Marsh.
Tomorrow Obama will wind up his visit after a more intimate meeting with about 20 Maori women leaders who are part of the Wahine Toa network set up by Nancy Gilbert, the wife of former ambassador Mark Gilbert.