Earlier Australia looked on course for the gold medal match after crushing England 27-12 in the quarter-final before losing after the siren to Canada 15-10 in the semi-final.
A third of the way through the qualifying process, the Langford-based Canadian women's rugby sevens team appears well positioned for the 2020 Tokyo Olympics.
The next round is in South Africa next weekend with New Zealand drawn against the hosts, Samoa and Zimbabwe.
Tries from Samuel Motari and Jeff Oluoch fell short as the Fijians gave new Kenya Sevens head coach Paul "Pau" Murunga a rude welcome to the World Rugby Sevens Series.
With just nine players in the Final, the All Blacks Sevens again faced the US and tries to Ng Shiu, Collier and McGarvey-Black confirmed the 21-5 result. New Zealand, with the choice of scrum or lineout, chose a quick throw in which caught the U.S. napping and Collier lumbered 60 metres to the posts.
The Blitzboks will try to make it a three-from-three wins on Day1 of the Dubai7s.
Fiji and South Africa will contest the fifth-place final.
Although there has been no official confirmation from World Rugby, a huge poster on display at The Sevens on Thursday said the 2019 edition to celebrate the tournament's 50th year would be held on December 5, 6 and 7.
To win the award again was wonderful, but is also challenging and I am super excited heading into the first day of competition in Dubai.
The next stage of the series takes place in Cape Town from 8-9 December.
"Obviously we talked about it, we were disappointed with how we went previous year but to come back and win here, its' one of the most incredible tournaments you can play in, its wonderful that we've taken home the silverware", said Goss.
"I'm so pleased with the girls' performances today - the amount of effort and work that everyone put in has been unbelievable", said Brown.
Canada has back-to-back podium finishes in the first two of six 2018-19 World Series tournaments, out of which the top-four teams at the end of the season will qualify for the Tokyo Summer Games.