Getting access to internet-capable TV could cost from as little as $69 for Chromecast, through to $1500-$2000 for a standard smart TV.
For viewers without internet access, delayed All Black pool games and several major live matches will also be shown on TVNZ.
IDC analyst Jefferson King said although connected TV numbers were low, viewing habits were shifting towards online and other devices such as laptops and smartphones, and the World Cup would probably be a catalyst for further change.
"The fact that the Rugby World Cup, probably the most important sporting event for New Zealand, is being streamed over the internet is a testament to the quality of our broadband infrastructure and shows how far it has improved in recent years," he said.
"This highlights how consumer behaviour is changing in New Zealand. It will be interesting to see whether the Rugby World Cup can be a catalyst to really drive digital disruption."
This was supported by research conducted by Trace Research last year, which found nearly half of New Zealanders now watch video online, with millennials watching 80 per cent of their video content online.
Just 6.8 per cent of households had TVs capable of 4K quality, but 17 per cent were planning to buy one in the coming year.
Trace Research director Andrew Zhu said the biggest barrier for this was bandwidth.
"With unlimited data widely available to service providers, the next competition is going to be on speed," Zhu said.
"People in the past would look at how much data they could get but now people are looking at speed. So in the next half year, all the ISPs will be focused on 5G technology, and faster internet."
There has been concern from rural regions about watching the World Cup, because some people don't have internet access, or are worried that their internet service will not handle streaming of the games.
IDC data showed by the end of 2016, about 86 per cent of households had internet access, but King said the issue was more about the quality of the service and how many households had fibre.
"It is interesting to note that only 28 per cent of households have a fibre connection, which is the best technology for streaming," King said.
"Although this has tripled in the two years since December 2015 and will continue to grow as the rollout of [ultra-fast broadband] continues."
Spark chief executive Simon Moutter said the move would make the games accessible to a much wider audience, and the company would work on ensuring good quality connections in the 18 months before the event.
A Spark spokesperson said most TVs purchased in the past few years would be internet-capable and consumers would have 18 months to buy a Chromecast or upgrade to a connected TV.
He said the company would be working to educate viewers on how to get connected ahead of the event.
InternetNZ deputy chief executive Andrew Cushen said the World Cup provided a great opportunity to showcase the country's internet infrastructure, which he said was world-leading.
"I think there is an underappreciation of how far we have come over the last 10 years," Cushen said.
"In my opinion, the number of people that can watch these games on the internet will be more than the number of people that would have watched them on TV via Sky, and that is just simply because the internet infrastructure is already in nearly every home in New Zealand."
"This is a challenge that Spark and TVNZ have to be up for, to show and teach and encourage New Zealanders to use this technology.
"If they do that right, New Zealand stands to win by showing what our infrastructure is capable of."
