The deal was confirmed in a meeting this morning.
Stuff Group owner and executive chair Sinead Boucher has told staff the 6pm bulletin will begin on July 6, the day after Newshub's final broadcast.
"It will be a great chance for [our journalists] to reach new audiences," one staff member reported her as saying.
She says Stuff won't be taking on the whole Newshub organisation.
The contract with Warner Bros will build on the strength of Stuff, she says.
"Stuff is always our priority.
"This is something extra that we will output."
It will be a one-hour bulletin Monday-Friday and 30 minutes in the weekends, but who fronts the bulletins is yet to be decided.
Boucher says Warner Bros Discovery wasn't willing to engage with potential media partners until after its proposal was confirmed last week.
Stuff will hire new talent for the bulletin, including technical staff, she says.
That will include some Newshub staff but Boucher would not say who or how many.
Stuff will also take over the Newshub website.
"It's got a big audience in its own right that we will be looking to migrate over to Stuff," Boucher said.
She reiterated that Stuff isn't buying Newshub.
"They are paying us to deliver a service and the Newshub website is coming free with the deal."
Bernadette Courtney, Stuff's editor in chief - newsrooms, spoke to RNZ following the meeting announcing the deal. She stressed that these were her own views.
"I think it's really exciting for Stuff and I think it's exciting for the media industry," she said.
"We're moving into a new area at Stuff - we're a successful digital company so why not expand into producing a news bulletin?"
Courtney said she couldn't comment on what it meant for jobs.
"We've just heard about this and there's a lot to process but there's an air of excitement in the newsroom."
Warner Bros Discovery's Glen Kyne said the Newshub announcement was "a difficult announcement today because we're not saving all the jobs in the newsroom".
It was positive for the country but it came with a "downside", so there were a range of feelings, he said.
A spokesperson for Media and Communications Minister Melissa Lee told Stuff the government had not been involved in facilitating the Stuff-Newshub agreement.
Lee's office would not comment when approached by RNZ.
