Having trailed 17-10 at the break, the Black Ferns dominated the second stanza, running in five tries at Ravenhill to claim their fifth global title.
The Kiwis were missed out in 2014 but their performances in Ireland have seen them re-establish themselves as the dominant force in women's rugby union.
Faamausili was full of praise for her colleagues in the aftermath of Saturday's win in Belfast, hailing the spirit they showed in fighting back to claim the cup.
Faamausili said: "I'm so proud of the girls, we dug deep, full credit to England, they really gave it to us, but I couldn't be prouder of the character of our team. We told them they'd have to go into deep, dark places and fight... and that's what they did."