Alongside Sky's NOW TV service, the STV Player was selected as the first additional service to launch on YouView of more than 300 expressions of interest from potential partners.
The Scottish broadcaster's video on-demand app is available now to access for YouView customers in STV licence areas of Scotland.
Viewers can watch STV programmes live and also catch up on shows from the ITV Network, such as Coronation Street, Emmerdale and The X Factor. The service is accessible via a dedicated STV Player app, or through the YouView programme guide.
STV chief technology and platforms officer, Alistair Brown, said: "YouView represents a major development in the evolution of TV in the UK offering an exciting new way for viewers to watch and move between live and catch-up TV.
"It is great that STV is one of the first content partners to go live on this new and innovative platform."
YouView chief executive Richard Halton added: "We are very pleased to have STV on board as one of the first content partners for YouView.
"STV is one of the UK's most popular television networks offering brilliant original content and it is great that their player is now live on YouView, giving users on-demand access to the channel."
Launched in July, the YouView set top box is the result of over three years' development of the multi-million pound project that is backed by the BBC, ITV, Channel 4, Channel 5, BT, TalkTalk and Arqiva.
The YouView receiver allows users to access all the Freeview channels in standard and high definition via a backwards-scrolling EPG, as well as browse the video on-demand libraries of ITV, STV, the BBC, Channel 4 and Channel 5.