With all votes counted, excluding special votes, the preliminary result put Tangaere-Manuel on 10,804 votes, compared to 7944 for Whaitiri.
The Ikaroa-Rāwhiti seat (on the Māori roll) covers a huge area of the East Coast from Gisborne down to Hutt Valley and has only been won by Labour candidates since it was established in 1999 - a streak which continued over the weekend.
Tangaere-Manuel said she was “still overwhelmed” and letting the result sink in.
“I’m so grateful to everyone who turned out for me, because I think it is a demonstration of their confidence that I will turn out for them,” she said.
“Before I went to the marae [on Saturday] night, I went to visit our urupā, our cemetery, to see my parents and all those who have gone before me.”
She said her parents would have been proud and she credited them with where she was now, as they “were servants of the community”.
“To carry that with me and thinking of Parekura Horomia, and to be able to retain the seat in his honour, was absolutely important to me.”
Horomia was a long-standing Ikaroa-Rāwhiti Labour MP up until his death in 2013.
Tangaere-Manuel said she believed it was because of Horomia’s legacy that many voters in the electorate felt such a strong affinity with Labour.
Tangaere-Manuel, who is married and has eight siblings, said her short-term plan was to get across the rohe “and say thank you in person”.
Meanwhile, Whaitiri posted on social media on Sunday that she would not be returning to Parliament for the first time in a decade.
“To my supporters and volunteers, thank you from the bottom of my heart. Our movement is here to stay,” she wrote.
“In signing off - let me be clear, I will not be returning to Parliament on the list - but like I said, the movement is bigger than any individual.
“What the future holds for me is yet to be determined, but I appreciate the kind words I have received.”
Whaitiri is number three on Te Pāti Māori’s list, but the party - according to the preliminary results - has only won candidate seats and no list seats.
FULL RESULTS - IKAROA-RĀWHITI
TANGAERE-MANUEL, Cushla - 10804
WHAITIRI, Meka - 7944
TUHAKARAINA, Ata - 636