In the coming weeks, adverts will start appearing inside the Resolution Games title Blaston as well as two other unnamed apps.
Facebook will later expand the system based on user feedback, saying it aims to create a "self-sustaining platform" for VR development. Quite who the user is that wants their virtual reality experience to feature an advert is unclear.
Facebook introduced ads on the Oculus mobile app last month, and it's used limited Oculus data to target Facebook advertising since 2019, but this is its first major foray into putting ads inside the Oculus VR platform itself.
"Once we see how this test goes and incorporate feedback from developers and the community, we'll provide more details on when ads may become more broadly available across the Oculus platform and in the Oculus mobile app", the company wrote in a blog.