Jedinak was handed the armband for Australia's last friendly against Ecuador and will now retain it for the Brazil campaign, where the Socceroos have been grouped with world champions Spain, the Netherlands and Chile for the opening round.
"It is a privileged position and an accolade he richly deserves after the incredible job he has done at Crystal Palace in the toughest club competition in world football the English Premier League," coach Ange Postecoglou said.
"I have no doubt he will lead the team with distinction in Brazil and we will have two of our greatest-ever football players in Tim Cahill and Mark Bresciano giving the team what I believe is strong leadership.
"Mile will be our captain but all three players will share the onus of leading this group to the World Cup."
Jedinak, 29, played every minute of Palace's recently concluded Premier League season until he was forced off the pitch with a groin strain in the second half of their final game.
Palace staged a remarkable comeback in the second half of the season to move out of relegation trouble before finishing 11th in the English top flight.
Australia will need something even more spectacular if they are to progress from a World Cup group that includes the two finalists from four years ago along with the third-placed team in South American qualifying.
Jedinak, who won his 43rd cap in the 4-3 defeat to Ecuador, will be expected to anchor the Australia midfield and help protect what will be a relatively inexperienced defence.
Neill, Australia's central defensive stalwart for more than a decade and captain for the 2006 and 2010 World Cup campaigns, was left out of Postecoglou's squad after failing to get enough first team play this year.
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- English Premier League
- Ange Postecoglou