The last product made at the Dunedin factory was Pineapple Lumps which rolled off the production line on March 23, ending the brand's 150-year legacy in Dunedin.
Around 350 employees lost their jobs following the closure, and Kiwi favourites have since been made by Mondelēz in Australia.
RJ's will supply the first batch of Jaffas to the New Zealand market on October 22. It is currently gearing up to go into production this week.
Law said the Jaffas would taste no different to the ones currently made by Mondelēz.
"We have done blind taste tests and nobody could tell the difference."
RJ's is producing the Jaffas under a license agreement with Mondelēz, and does not own the rights to the brand.
"It's really important to try and keep iconic brands in New Zealand. Jaffas have been around for a long time so what we want to do is keep that brand here," Law said.
"Joining it to the RJ's family is excellent for our brand."
Mondelēz International associate director Paul Chatfield said the confectionery giant was happy to pass over the production responsibilities to RJ's.
"We're excited to work with RJ's to keep the Jaffas brand strong in New Zealand, particularly because RJ's has a proud Kiwi heritage," Chatfield said.
"We were committed to ensuring consumers could still get their hands on the most fun chocolate orange ball ever, and we've achieved that with this agreement."
Oamaru lolly maker Rainbow Confectionery last year expressed interest in manufacturing Mondelēz's full portfolio of Cadbury's Kiwi products but the company declined the offer.
In October, Mondelēz said it would manufacture the products, including Jaffas and Pineapple Lumps, in Australia.
It said the requirements of these products, particularly the marshmallow-based products, meant it "simply wasn't possible" to have them manufactured locally, despite having worked closely with one manufacturer on the possibility.
RJ's was set up 23 years ago by Roger Halliwell, Law's father. It is now owned by Australian investment company Quadrant Private Equity.
RJ's makes a range of liquorice lollies, including Licorice Logs and Twisters, producing five million kilograms of liquorice per year.