Work will focus on redeveloping the West and North Stands to elevate Elland Road to the seventh-largest ground in England.
The club has not set a timeline for the staged stadium upgrade which is going out to public consultation in May.
Specialist sports architect KSS has been signed up to design the project, alongside structural engineer Buro Happold.
Project management will be led by RISE, with the Lowy Family Group acting as development partner for the wider regeneration of the area.
The upgraded stadium will meet UEFA Category 4 standards, paving the way for international fixtures, concerts, and events.