From 5pm, ITV3 HD will start broadcasting at channel 226 on Sky's electronic programming guide, while ITV4 HD will be available at position 227.
The channels will broadcast a range of programmes in native high definition. The rest of their schedules will be upscaled to the higher picture quality.
ITV4's native HD schedule will include races from the Dunlop MSA British Touring Car Championship, after ITV recently extended its rights deal to the sport.
The two channels follow the launch of ITV2 HD last month at position 225 on Sky's programming guide. The exclusive channels are part of ITV's new pay-TV strategy.
Announcing the strategy in August, ITV chief executive Adam Crozier said: "Building new revenue streams by exploiting our content across multiple platforms is a key part of the ITV transformation plan.
"Pay television has seen continual growth over the last decade and this deal is a great example of how a new, subscription-based launch, can complement ITV's existing free-to-air channels."
Sky's chief operating officer Mike Darcey added: "The subscription model best rewards those committing to HD and continues to drive its growth.
"We therefore welcome ITV's move to embrace pay-TV to satisfy the demands of millions who now regard anything less than HD as a compromise."