Ashcroft joined the Lions as the second overall pick in Monday's National Draft, following in the footsteps of his father Marcus, who played 318 games with for Brisbane, winning three premierships.
While the champion Lion wore No.10 for 308 games, his oldest son Will won't be able to have the same locker number given Brisbane veteran Daniel Rich still occupies that guernsey.
Ashcroft will be just two lockers down from Rich, while star recruit Josh Dunkley will be another three spots down as he pulls on the same number he wore with the Bulldogs in No.5.
That number was made vacant after Mitch Robinson's departure this off-season.
Brisbane Lions' new jumper numbers
5 - Josh Dunkley
8 - Will Ashcroft
13 - Blake Coleman
19 - Jack Gunston
25 - Henry Smith
26 - Conor McKenna
28 - Jaspa Fletcher
34 - Shadeau Brain
50 - Darryl McDowell-White