Holman, who has earned 63 international caps, was originally overlooked for Thursday morning's (AEDT) clash in London, with Ange Postecoglou opting for a youthful 23-man squad.
However, a hip injury to Halloran has opened the door for the 29-year-old Al Nasr midfielder, who has not featured for the national team since September's 6-0 drubbing in Brazil.
"I look forward to having Brett in the camp and for the Ecuador game," Postecoglou said.
"He has proven himself on the international stage and it will be good to get Brett into the group so he can get a feel for what we are trying to achieve."
An ever-present during Holger Osieck's tenure, Holman will have the opportunity to stake his claim for a ticket to Brazil having gone off the radar since he controversially moved to Dubai from English Premier League outfit Aston Villa in 2013.
Halloran, 21, was set to make his debut Socceroo debut at The Den after a number of eye-catching performances for Fortuna Dusseldorf in German's second tier.
The former Brisbane Roar attacker, seen by many as a potential replacement for Robbie Kruse in Brazil later this year, will remain in Germany to continue treatment on his injured hip which ruled him out of Fortuna's trip to Bochum last week.
"Ben was under a cloud and we received some further information about his injury, which showed it was in Ben’s best interest that he was ruled out of the game," said Postecoglou.
"It's a shame for Ben because he deserved the opportunity to make an impression at the camp and we will continue to watch him in the lead up to the World Cup."
