It was England's first victory away in New Zealand since 2001 and followed wins against Australia and Canada in the four-team tournament.
The Red Roses recovered from 14-7 down after 30 minutes to win a ninth game in a row on Sunday.
Emily Scarratt, Abbie Scott, Lydia Thompson, Marlie Packer and Vicky Fleetwood scored the tries.
"With analysis we can look at what we have to improve on but we needed to give everything against the best side in the world. We've done that and so are rightfully very happy and very proud," said head coach Simon Middleton.
England are preparing for the Women's Rugby World Cup, which takes place in Ireland and starts in Dublin on Wednesday, 9 August.
"We have built through the series and to come out and to put in a performance like that against New Zealand is something we're very pleased and happy about," said England captain Sarah Hunter.
"We wanted to stick to our processes, stay patient and that's exactly what we did. We took everything we've been doing in training onto the pitch."
England beat New Zealand 29-21 in Rotorua to finish the International Women's Rugby Series unbeaten.