The agreement will add the Discovery Channel, Animal Planet and Real Time to BT Vision, and it also includes a range of video on-demand every week.
This follows a similar deal between BT and Eurosport for channels and on-demand.
Discovery Channel broadcasts various documentaries and factual entertainment shows, including How We Invented The World, Gold Rush and Wheeler Dealers.
Programmes available on Animal Planet include Monster Bug Wars and Koala Hospitals; and Real Time viewers can enjoy shows such as Cake Boss and Auction Kings.
BT said the three new channels will be available to BT Vision viewers "shortly".
Marc Watson, chief executive BT Vision, said: "The new channels are a great addition to our lineup. We're really excited about the deal with Discovery Networks.
"It will offer BT Vision viewers some of the most well-known and popular factual programmes in the UK."
Discovery Networks UK & Ireland general manager Susanna Dinnage added: "We are delighted to have completed this deal which gives us the opportunity to share three of our key channels with BT Vision's customers.
"Discovery Channel is the most popular factual channel in pay-TV and we are delighted that it is now also available on BT Vision."
The Discovery deal follows a similar agreement between BT and Eurosport for the carriage of British Eurosport and British Eurosport 2 on BT Vision, along with a range of video on-demand content.
BT also recently secured channel deals for FX, National Geographic, National Geographic WILD and UKTV's Gold, Watch and Alibi, as it looks to expand its television offering.