The telecoms giant's new target is a year ahead of its original plan, and the firm also confirmed that it would double the speed of its BT Infinity fibre-to-the-cabinet (FTTC) product to around 70-80Mbps.
The news follows a recent announcement that BT will offer broadband of up to 300Mbps by next spring, as it moves to fend off strong competition from Virgin Media's fibre network.
BT said that it is bringing forward around £300m of investment over the next few years to fund the accelerated rollout programme. The firm intends to invest £2.5bn in total on commercial fibre rollout, using both FTTC and the more costly fibre-to-the-premises (FTTP) technology.
The company intends to employ 520 new engineers to assist with the broadband deployment, most of whom will be ex-armed forces personnel.
The new rollout strategy is part of BT's renewed commitment to help the government meet its ambition of having the best superfast broadband in Europe by 2015.
Ministers believe that access to high-speed internet is essential for the future of the UK economy, but Britain currently ranks as having the 25th fastest web in the world, and only the 15th fastest in Europe.
Culture secretary Jeremy Hunt said: "Superfast broadband is essential for achieving sustainable growth and it is vital that homes and businesses have access to it as soon as possible.
"BT's accelerated fibre rollout plan is great news for the UK. With access to superfast broadband UK businesses will have the infrastructure they need to grow and develop new products and services. This investment means new jobs today, but also allows us to build the digital infrastructure we need for the jobs of tomorrow.
"The government is committed to ensuring the UK is leading the way in broadband provision and BT's accelerated rollout will help make that a reality."
BT Group chief executive Ian Livingston added: "Our rollout of fibre broadband is one of the fastest in the world and so it is great to be ahead of what was an already challenging schedule.
"The acceleration reflects the success of the programme to date and is testament to the hard work and innovation of our people. We are investing when others are merely talking about it."
BT's fibre broadband is already available to six million premises across the UK. That figure will rise to 10m in 2012 and then two-thirds of premises by the end of 2014.
The fibre network will also be made available on a wholesale basis to other providers, with TalkTalk and fibre rival Virgin Media already indicating that they will take up the offer.
BT is also bidding for a portion of the government's allocation of £530 million over the course of this parliament to bring fibre broadband to remote areas, particularly in rural communities.
Livingston said: "Thousands of our engineers are busy installing fibre broadband across the UK at an astonishing pace. The recruitment of an additional 500 engineers will help us go even faster and ensure we are ready to help supply other areas should we win [government] funds. We are proud that most of these jobs will be filled by ex-armed forces personnel."
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