The pair will act as coaching consultants during the three-match one-day international series against New Zealand in January and February, Cricket Australia said.
Harris will concentrate on bowling, with regular coach David Saker heading to India early with batting coach Graeme Hick to prepare for the test series starting in February.
Haddin, who joined Harris in retirement last year, will be employed as a fielding consultant.
“It’s a fantastic opportunity for us to have ex-players of the calibre of Brad and Ryan on board for this tour and continue their involvement in Australian cricket," head coach Darren Lehmann said in a media release.
“Both these guys have worked hard on their coaching since leaving the game and thoroughly deserve their opportunity.
“They will bring a great insight to the team and their appointment highlights some of the depth we have in Australia in the coaching pathway system."
Haddin, 38, has been involved preparing the next generation of talent in the Australia 'A' side, while Harris, who has aspirations of becoming the team's next head bowling coach, was an assistant during the one-day international team's recent 5-0 whitewash by South Africa on tour.
“South Africa was a great learning experience for me and it was fantastic to be back with the team again," said Harris.
Australia's coaching staff have been under the microscope, with both the test and one-day teams struggling in recent months.
Australia's series-opening loss to South Africa in Perth on Monday was its fourth defeat in succession after the 3-0 whitewash in Sri Lanka.
The second test against the Proteas starts on Saturday in Hobart.
(Reporting by Ian Ransom; Editing by Frank Pingue)
