South Korea's parliament on Tuesday (Aug 31) approved a bill taking action against big tech firms.
It will ban major app store operators such as Google and Apple from forcing software developers to use their payment systems.
That will effectively stop them from charging commissions on in-app purchases.
It is the first such curb by a major economy on the likes of Apple and Alphabet's Google.
The U.S. giants face global criticism for requiring the use of proprietary payment systems that charge commissions of up to 30%.
South Korea's Telecommunications Business Act has been dubbed the "anti-Google law."
A Google spokesperson told Reuters that it will "reflect on how to comply with this law while maintaining a model that supports a high-quality operating system and app store".
Apple responded to an email reiterating a statement issued last week.
Saying: "We believe user trust in App Store purchases will decrease as a result of this proposal - leading to fewer opportunities for the over 482,000 registered developers in Korea".