The 35-year-old makes the switch to the A-League Champions from crosstown rivals Melbourne City where he coached last season.
Vanstrattan spent the majority of his playing career in Italy, including a stint at one of the world's most famous clubs, Juventus.
He replaces Dean Anastasiadis, who steps away after three seasons with Victory where he helped shape the career of Joe Marston medallist Lawrence Thomas.
Victory coach Keving Muscat said: "Jess played at some big clubs and he's been coaching for a few years now, so we think he'll be real asset to us moving forward."
"We saw how well Lawrence played throughout the finals series and a lot of that was attributable to Dean and the work he's done with all of our keepers over the past three seasons.
"I'd like to formally thank Dean for his positive contribution to the club and wish him all the best.

"Dean's decision to return to work in the family business has opened the door for Jess to come on board and bring with him a slightly different approach to training, which I'm sure Lawrence, Matt Acton and young Matt Sutton will really relish."

Vanstrattan will link up with the team on July 9.