The New South Wales wicketkeeper-batsman and South Australian fast bowler Shaun Tait were the main selection talking points in the 15-man squad released by selectors for next month's World Cup in the Caribbean on Tuesday.
Amid reports that Gilchrist may be allowed to take compassionate leave during the early stages of the World Cup campaign for the birth of his child, Haddin was included in the squad as back-up.
"Brad has been selected on the back of some fine domestic performances this year for New South Wales," chairman of selectors Andrew Hilditch said.
"We see him capable of batting everywhere in the order and he gives us massive flexibility for the Cup.
"In addition, he provides us with cover as a second wicketkeeper should Adam Gilchrist become injured during the tournament."
Hilditch said Tait's selection ahead of Stuart Clark, one of Australia's stars in last month's 5-0 Ashes Test series win over England, was a difficult decision.
"Shaun has been selected and it is fair to say it was a difficult decision to make on Stuart, who has been part of the squad this summer," Hilditch said.
"Shaun's pace will give us extra firepower during the power plays and at the end of the innings and adds variation to the pace attack for the World Cup."
Clark can consider himself desperately unlucky to miss out after taking a hat-trick in a 10-wicket match haul for NSW in last weekend's Sheffield Shield match with Western Australia in Perth.
Another notable omission was Victorian leg-spinner Cameron White, who was tried in this month's tri-series against England and New Zealand.
"Cameron is extremely unlucky to miss selection in the squad. He is a young man with a bright future for Australia," Hilditch said.
"We think he'll only get better with age. The reality is that since Cameron was picked in the squad, Shane Watson has returned and Brad Hodge has seized his opportunity, meaning Cameron has missed out."
Hilditch said selectors chose injured all-rounder Andrew Symonds in the squad after discussions with team medical staff.
Symonds injured a bicep muscle in the latter stages of the tri-series and had surgery.
"After lengthy discussions with the medical staff Andrew has been selected," Hilditch said.
"His recovery from surgery has gone as well as could have been expected and given his importance to the team and the balance of the team it was felt that the risk of picking him so soon after surgery is warranted."
Hilditch is confident selectors have chosen a squad capable of winning three straight World Cups.
"We have been planning for the defence of the ICC Cricket World Cup for two years," he said.
"We've been pleased with the team's preparation and extremely pleased with the victory in the recent ICC Champions Trophy.
"This squad represents a balance of experience and youth and is capable of winning the ICC Cricket World Cup for the third time in a row."
The Australians open their World Cup campaign against Scotland in St. Kitts on March 13.
Australia's World Cup team: Ricky Ponting (captain), Adam Gilchrist, Matthew Hayden, Michael Clarke, Mike Hussey, Brad Hodge, Shane Watson, Andrew Symonds, Brad Haddin, Brad Hogg, Brett Lee, Mitchell Johnson, Shaun Tait, Nathan Bracken, Glenn McGrath.