Haddin, who has represented Australia in 66 Tests and 126 ODIs, will be joining the squad for their upcoming tour of Bangladesh. He has been contracted until the end of 2019.
"I am thrilled to get the opportunity to work with this young group of players," Haddin said in a statement. "I grew up in an era of players like Andrew Symonds and Ricky Ponting who gave Australian cricket a real identity in the standards of world-class fielding. They were the type of players who took it personally if the team wasn't fielding well and that created a level for the rest of the group to aspire to."
Haddin assisted the New South Wales Under-17 and Under-19 squads soon after his retirement post the 2015 Ashes series. He shared coaching duties with his former Test team-mate Ryan Harris during Australia A's matches against India A and South Africa A in Townsville in 2016. Earlier this year, both men assisted the national side during their tour of New Zealand.
"I want to hold this group accountable to that kind of standard and I believe we have the talent to do that. It will be hard work but I am looking forward to the challenge," he said. "Given my background is in wicketkeeping it will be great to be able to work with the 'keepers in the side and give them a sounding board."
Both Haddin and Blewett are currently with the Australia squad in Darwin for a training camp ahead of the tour of Bangladesh. At the end of the camp, Blewett is expected to return home and Haddin will accompany the Australia players to the subcontinent.
Blewett, who had been Australia's fielding coach since August 2014, will now be in charge of South Australia's Under-19 team, apart from assisting the Redbacks in domestic cricket and the also Adelaide Strikers in the Big Bash League.
"I'm very passionate about cricket in this state," Blewett told News Corp. "Clearly there also was the lure of spending more time at home with my young family because I've lived a fairly selfish existence most of my life with all of the travelling for cricket.
"But I also want to help the Redbacks squads achieve good things, along with trying to broaden my coaching experience."