BT Ireland and Sky Ireland have done a deal that sees the TV company tied into BT's network on a four-year contract.
The value of the wholesale deal was not disclosed.
The arrangement will see Sky using BT's network for broadband and other services. BT has approximately 4,300km of fibre network in Ireland. It uses this fibre, together with fibre from other companies' networks, as a wholesale service to customers such as Sky.
The deal is also intended to serve some of the 542,000 rural customers in the National Broadband Plan catchment area when the government announces a winning bidder next year.
"This deal with BT reflects our continued commitment to investment in infrastructure in Ireland and will mean our customers can avail of the highest fibre speeds in the country across the widest possible footprint," said JD Buckley, managing director of Sky Ireland. "It will also allow us to bring fibre to currently underserved rural customers as part of the Government's National Broadband Plan."
The deal was the culmination of a tender put out by Sky to wholesale telecoms firms.
BT claims to be the only "access agnostic" provider of wholesale broadband services in Ireland. It says that more than 50 communications companies use its network in Ireland.
The move comes after the number of shortlisted bidders for the National Broadband Plan shrank from three to two with the exit of ESB-Vodafone joint venture Siro from the process.
Siro claims that the tender is no longer commercially viable for its interest after the Government did a deal with Eir for the removal of 300,000 premises from the catchment area.