Tom Rogic and Mark Birighitti were also cut as Australia - who reduced their preliminary squad to 27 last week – continue their preparations for the Brazil showpiece.
But it is the absence of Kennedy and Wilkshire that will grab the headlines, with the experienced pair both having represented Australia at the 2006 and 2010 World Cup.
"Every step of the selection process has been difficult because the players have worked very hard since they came into camp but we have had to weigh up form, fitness and squad balance in coming up with the 23 players who will represent Australia at the 2014 World Cup," Postecoglou said on Football Federation Australia's website.
"We've selected a squad that can do Australia proud and they will walk out onto the pitch for the World Cup in the green and gold shirt and display the characteristics that define our country."
Kennedy has managed just eight games for Nagoya Grampus in this J.League season, scoring four goals, as he continues to manage a back issue, which forced him of Australia's 2-0 friendly win over Parana Clube on Monday.
Last season's A-League top scorer, Newcastle Jets forward Adam Taggart netted in that game to suggest Kennedy's absence may not be keenly felt, despite him scoring the goal that secured Australia's place at the World Cup.
Heading the list of those five is Australia's all-time top scorer Tim Cahill, and he is joined by Mark Bresciano, Mile Jedinak, Dario Vidosic and Mark Milligan.
Postecoglou's men begin their campaign with a crucial clash against Chile in Cuiaba on June 13.
