The former Brisbane Roar forward won Australia's 'Golden Boot' with Melbourne Victory's Besart Berisha after scoring 19 goals in the domestic A-League's regular season, and is back in the frame after missing the previous two qualifiers against Iraq and United Arab Emirates.
The 23-year-old, who has signed for Darmstadt in Germany's second division, joins veteran striker Tim Cahill and Tomi Juric in the squad, as Postecoglou looks for more firepower to help secure a fourth successive World Cup appearance.
"He gets an opportunity I guess, certainly his back half of the year was very strong and scored goals," Postecoglou said of Maclaren, who has been capped twice for Australia after representing Scotland at youth level.
"We're certainly going to need some depth in all areas. It's gong to be a challenging month."
Australia ended a run of four successive draws with their 2-0 win over the UAE in Sydney in March but sit third in Group B of Asian qualifying, three points behind Japan and Saudi Arabia.
Only the top two teams qualify automatically for Russia, with the third-placed team going into a playoff.
Australia host Saudi Arabia in Adelaide on June 8 before heading to Japan in August and returning home for the last qualifier against Thailand in September.
Postecoglou has included six uncapped players, including Portugal-based defender Dylan McGowan, the younger brother of Socceroos regular Ryan McGowan, and 20-year-old Netherlands-based winger Ajdin Hrustic.
"Ajdin's been on our radar for a while and this year he's had a bit of a breakthrough in Holland and did very well at the under-23 camp," said Postecoglou.
"He's technically very good and one we think would benefit from being in that environment."
Midfielder Tom Rogic returns from injury after winning another Scottish championship with Celtic but former stalwart defender Rhys Williams has been cut.
The squad, which will be trimmed to 23 next week, will also play Brazil in a friendly in Melbourne on June 13 before heading to Russia for the June 19-July 12 Confederations Cup where Australia have been drawn with Germany, Chile and Cameroon in Group B.
Squad:
Goalkeepers - Mark Birighitti, Mitch Langerak, Mat Ryan, Danny Vukovic
Defenders - Aziz Behich, Milos Degenek, Alex Gersbach, Rhyan Grant, Dylan McGowan, Ryan McGowan, Trent Sainsbury, Brad Smith, Bailey Wright
Midfielders - Mustafa Amini, Craig Goodwin, Ajdin Hrustic, Jackson Irvine, Mile Jedinak (captain), James Jeggo, Robbie Kruse, Mathew Leckie, Massimo Luongo, Riley McGree, Mark Milligan, Aaron Mooy, Tomi Rogic, James Troisi
Forwards - Tim Cahill, Tomi Juric, Jamie Maclaren
(Reporting by Ian Ransom; Editing by Greg Stutchbury/Peter Rutherford)
