Starting next year, teams participating in the Vodacom Cup will have to field seven black players in their 22-man squad, five of whom must be fielded among the starters and two of whom must be forwards.
"This decision to introduce measurable targets underlines SARU's commitment to transformation," SARU president Oregan Hoskins said in a statement.
"The Vodacom Cup is a critical step on the development pathway in professional rugby but it had moved away from its primary purpose of presenting opportunities for young emerging players, particularly black players.
"This is rugby's tangible step on delivering on a pledge (to transform). The intended outcome is an increased pool of black talent from which Currie Cup and Super Rugby coaches can select and - in due course - more options for the Springbok coach," Hoskins added.
The Vodacom Cup is a domestic competition featuring the country's 14 provincial unions and takes place in the first half of the year, at the same time as the Super Rugby competition.
Racial quotas in South African sporting codes previously dominated by minority whites since the fall of apartheid have become less contentious in recent years but have previously made for heated debate.
There has never been an official quota system in South African rugby, although it has been commonly accepted that Springbok squads would have at least three black players named.
The 30-man Springbok squad named for their first two matches of the Rugby Championship features nine black players.
Their first match is against Argentina in Soweto on Saturday.