From Monday (March 18), Sky customers who have connected their Sky+HD box to broadband will be able to catch up on shows from Channel 4's portfolio of networks, including Channel 4, E4 and More 4.
Programming from the Channel 4 archive, such as The Inbetweeners, Shameless, Spaced, Father Ted, The IT Crowd and This Is England '88, will also be available on Sky On Demand.
Sky also said that its 4.5 million HD customers are getting access to the More4 HD channel, and Film4 HD will join the platform in September.
Last year, Sky launched Sky On Demand offering both catch-up and on-demand television. The service went live with ITV Player and Five On Demand, but later expanded to BBC iPlayer and soon 4oD, meaning it will offer all the on-demand platforms of the major UK broadcasters.
Users can also access on-demand content from Sky1, Sky Atlantic, Sky Living, Sky Arts, the History Channel, National Geographic and others.
Sky estimates that the total number of connected Sky+HD boxes has now surpassed two million, and continues to grow.
As well as 4oD joining Sky On Demand, Channel 4 will also become the first terrestrial network to offer its channels and programmes on Sky Go, the Sky multi-platform TV service.
From Monday (March 18), Sky Go users will be able to stream Channel 4 and More 4 live on their laptop, smartphone, or tablet, with E4 and Film4 to follow shortly. Selected Channel 4 content will be available on-demand on Sky Go.
Sky's director of TV products, Luke Bradley-Jones, said the way people are enjoying TV is changing with the rise of on-demand and multiple screens.
"We know customers have busier lives than ever, which is why we've created the most comprehensive catch-up service in the UK," he said.
"Over 2 million Sky customers have already connected their Sky+ box to the internet so they can enjoy our full catch-up and On Demand service.
"But we are working hard to get even more Sky homes connected as we know our customers love the control and flexibility it gives them - it's a perfect complement to Sky+."
Channel 4's director of commercial & business development, Sarah Rose, added: "The launch of our successful VOD service, 4oD, on the Sky on demand and Sky Go platforms this month will extend the reach of our content to enable even more viewers to enjoy our wide range of programmes.
"And through the recent arrival of More4 HD and much anticipated launch of Film4 HD in September, we're delighted to complete the roll out of our HD portfolio."