Hamilton will host a combined men's and women's rugby sevens tournament from next season.
The women's circuit will increase to eight tournaments with six of those combined with the men.
The men's series will remain at ten rounds.
New Zealand Rugby Chief Rugby Officer Nigel Cass said NZR is considering co-hosting the tournament with Fiji during the 2020-2023 cycle.
"Everyone has seen the contribution of the Fijian rugby community to the success of the tournament in Hamilton both on the field and in the stands. An option being looked at is alternating the tournament between Hamilton and Fiji and early negotiations are promising."
Fiji Rugby Union Chief Executive John O'Connor said it was an exciting time for Fiji's rugby community.
"We are grateful to NZR for offering to alternate the hosting of the New Zealand Sevens with Fiji and we're confident of delivering an amazing experience for everyone involved.
Dubai, Cape Town, New Zealand, Sydney, Hong Kong and Paris will host combined events from next season onwards as part of the next four-year world series hosting cycle.
World Rugby said it received more than 20 expressions of interest from member unions, as part of the highly competitive tender process.
Hamilton, the newest venue on the men's series having hosted its inaugural event in 2018, becomes a new combined event for both men's and women's teams.
World Rugby Chairman Sir Bill Beaumont said: "This is an exciting time for sevens as the World Rugby Sevens Series is set to break new ground with more combined rounds than ever before on the circuit, as Cape Town, Hamilton and Hong Kong welcome women's world series teams for the first time from next season.
"We are delighted to see the women's series expand to eight rounds over the next four-year cycle, an historic move that will provide more high quality competitive international playing opportunities for women's sevens teams, a core strand of our Accelerating the Global Development of Women in Rugby plan.
"For the men's series, the selected hosts represent a consistent balance of long-established and newer venues, with the five host unions who joined in 2015 retaining their host status.
"Since the men's series' expansion to 10 rounds in 2015, we have seen the competition become increasingly competitive on the pitch from a team perspective while also continuing to grow in popularity among global audiences. We are looking forward to seeing continued growth and evolution of the world series in each territory over the next four years."
The full men's and women's World Rugby Sevens Series 2019-20 schedule and dates will be confirmed at a later stage in 2019.