BT will also have to wholesale its infrastructure of telegraph poles and underground ducts in a bid to increase competition for superfast internet to rural areas.
The decision supports government plans laid out earlier this year to prevent a “digital divide” making rural areas commercially unviable.
TalkTalk has already announced it will sign up to the new scheme to offer broadband speeds of over 25 megabits per second to its customers.
Ofcom said it will not immediately cap the prices BT is able to charge for access to its infrastructure but they will be subject to review and could be slashed if deemed anti-competitive.
Ofcom’s chief executive, Ed Richards said: “The development of the UK’s superfast broadband future is well underway with the roll-out of services in large parts of the country.
“Today Ofcom has finalised a clear regulatory framework to promote investment, competition and innovation to enable as many consumers as possible to benefit from these exciting new services.”
The ruling means BSkyB will be able to offer superfast broadband to rural homes for the first time, opening up a new front in the war between the two media giants.
Sky was incensed by a ruling earlier this year forcing it to wholesale its Premier League football to rivals including BT and Virgin Media for a fixed price.
The move allowed BT to mount a serious challenge to Sky’s dominance in the pay-TV market for the first time. However, BT has refused to announce subscriber figures amid rumours it has failed to convince its customers to sign up.