The 21-year-old English-based central defender, who has yet to play for his country, was one of two unexpected picks, along with Fortuna Dusseldorf forward Ben Halloran.
Only eight players – Tim Cahill, Josh Kennedy, Mark Milligan, Mile Jedinak, Mark Bresciano, Luke Wilkshire, Eugene Galekovic and Dario Vidosic – remain from the squad that went to South Africa for the 2010 World Cup.
Goalkeeper Mark Schwarzer, former captain and defender Lucas Neill, forward Harry Kewell and midfielders Brett Emerton and Brett Holman have all announced their international retirements in recent times, leaving the Socceroos in a state of transition.
“The squad has been selected with form and fitness as key indicators as well as having one eye on the future,” said Postecoglou.
“We face a formidable challenge in Brazil but it is also a big opportunity and we head to the World Cup with no barriers as we look to write a new chapter in our rich football history.”
Australia will face reigning world champions Spain, Netherlands and Chile in Group B. Chile are their first opponents in Curitiba on 13 June with the squad heading to Brazil on 28 May.
Goalkeepers: Mat Ryan (Club Brugge/Belgium), Mitch Langerak (Borussia Dortmund/Germany), Eugene Galekovic (Adelaide United), Mark Birighitti (Newcastle Jets)
Defenders: Ivan Franjic (Brisbane Roar), Matthew Spiranovic (Western Sydney Wanderers), Curtis Good (Newcastle United/England), Bailey Wright (Preston North End/England), Jason Davidson (Heracles Almelo/Netherlands), Luke Wilkshire (Dynamo Moscow/Russia), Alex Wilkinson (Jeonbuk Motors/Korea Republic), Ryan McGowan (Shandong Luneng/China PR)
Midfielders: Mile Jedinak (Crystal Palace/England), Mark Milligan (Melbourne Victory), James Holland (Austria Vienna/Austria), Massimo Luongo (Swindon Town/England), Adam Sarota (FC Utrecht/Netherlands), Oliver Bozanic (Luzern/Switzerland), Matt McKay (Brisbane Roar), Mark Bresciano (Al Gharafa/Qatar), Josh Brillante (Newcastle Jets)
Forwards: Tim Cahill (New York Red Bulls/USA), Josh Kennedy (Nagoya Grampus/Japan), Tom Rogic (Melbourne Victory), Dario Vidosic (Sion/Switzerland), Tommy Oar (FC Utrecht/Netherlands), James Troisi (Melbourne Victory), Ben Halloran (Fortuna Dusseldorf/Germany), Adam Taggart (Newcastle Jets, Matthew Leckie (FSV Frankfurt/Germany)