During 2013, the telecoms giant will deploy the technology to another 29,000 properties in Culverhouse, Cwmbran, Gorseinon and Neath.
By the time the upgrades are finished, fibre optic broadband will be available to 570,000 premises across Wales, with 302,000 already connected to the service.
It is believed that BT's £2.5 billion investment in super-fast broadband will provide a substantial benefit to the Welsh economy.
A recent study from Regeneris Consulting claimed the technology will deliver a £143 million boost to a typical town over the next 15 years, as well as creating 225 new jobs and 140 start-up businesses.
Bob Palmer, vice chairman and CBI representative on the South West Wales Economic Forum, said: "This is excellent news for many people in these communities.
"Reliable, fast connections can make all the difference to businesses in a tough economic climate."
This is the latest in a string of recent Welsh fibre broadband announcements from BT.
In March, the company revealed that it will roll out the technology to 60,000 more properties in the Llanelli and Swansea areas by spring 2013.
June 26, 2012