The network operator said it is investing £2 billion in its infrastructure to support the new network.
5G technology is the next generation of mobile network and is expected to offer internet speeds several times that of current generation 4G. The company has suggested its own 5G network will be the fastest in the UK, claiming peak speeds could be more than twice as fast as its rivals.
Rival operator EE launched their 5G network last week, and Vodafone is due to begin rolling out its own network at the beginning of July.
Three’s rollout will begin with a 5G home broadband service in London, before expanding to other towns and cities including Birmingham, Brighton, Bristol, Cardiff, Edinburgh, Glasgow, Leeds, Liverpool, Manchester, Nottingham, Sheffield and Sunderland before the end of the year.
Three chief executive Dave Dyson said: “It’s clear that consumers and businesses want more and more data.
“We have the UK’s best network for data and we have led the market on customer usage on both 3G and 4G technologies. We have worked hard over a long period of time to be able to offer the best end to end 5G experience. 5G is a game changer for Three, and of course I am excited that we will be the only operator in the UK who can offer true 5G.”
Dani Warner, broadband expert at uSwitch.com, added:
“Three’s 5G plans will have significant repercussions across both the mobile and broadband industry, particularly with the announcement that 5G home broadband is part of the roll-out.
“Not only is Three’s 5G service set to be available in more cities than either Vodafone or EE, but the network is also confident its speeds will be twice as fast as those of its rivals.
“And Three users who are not yet fully on board with the 5G movement, or are reluctant to fork out for an upgraded 5G-ready handset, will also benefit from significant improvements to the network’s existing 4G service.
“However, it is the home broadband offering that really catches the eye. Until now, much of the discussion of 5G’s arrival has centred on how it will improve mobile connectivity and speeds, but its potential to upend the broadband market, and so quickly, is now being explored by Three.
“Those in areas or buildings without full fibre installed may now be able to choose the convenient option of plugging a 5G router straight into the wall and being online on ultrafast speeds in seconds.
“By the time full fibre does reach many people – with 2033 still the government’s target for full coverage – they may very well be perfectly happy with 5G mobile broadband connections.
“The traditional broadband heavyweights will be sitting up and paying attention as Three has fired a significant warning shot here. If it is competitively priced, 5G could well win the ‘space race’ with fibre in the next few years.”