Juric, who had A-League stints with the Reds and Western Sydney from 2013-15, has spent the past five years in Europe.
"I'm delighted to be coming back home ... Adelaide United has a good project in place, I'm excited to be a part of it," Juric said in a statement on Thursday.
The 29-year-old with 41 Socceroos caps returns after playing in the Netherlands, Switzerland, and most recently in Bulgaria with CSKA Sofia.
Adelaide United's football director Bruce Djite said Juric's signing was a coup for the Reds.
"We're delighted ... Tomi brings an abundance of experience and attacking prowess and he has played on some of the biggest stages in world football for the Socceroos," Djite said.
"The quality he will bring to our squad will be invaluable and I'm sure he will also be a fantastic mentor to our younger strikers."
Juric's signing follows Adelaide recruiting experienced Spaniard Javi Lopez for the A-League season starting in late December.
Lopez, 34, has spent the past 11 year in La Liga with RCD Espanyol, serving as captain for the past five years.