BT's investment in super-fast broadband is set to create £20 billion for the London economy over the next 15 years, it has been reported.
A new study conducted by Regeneris Consulting found that for every £1 invested in super-fast broadband, the firm will create £10 in gross added value.
The deployment of super-fast services will help create 26,000 jobs in the capital by 2027, it added.
BT is currently in the process of investing £2.5 billion upgrading its national broadband infrastructure to offer super-fast and ultra-fast download speeds.
By 2013, the broadband provider is aiming to offer up to 300Mb speeds to many households and businesses - with London properties among those set to benefit.
Two-thirds of UK premises - across more than 1,000 exchange areas - are to receive access to BT super-fast fibre broadband by 2014.
Stephen Nicol, managing director of Regeneris Consulting, said BT makes "a substantial contribution" to the global city that is London.
"Its direct contribution is particularly large and when the supply chain and other effects are added in the firm accounts for £1 in every £70 generated by the London economy," he stated.
"Clearly, its continued investment in super-fast broadband is proving critical to the competiveness of the UK's largest economy."
Chet Patel, BT's Regional Director for London, said the Regeneris Consulting report demonstrates the "great benefits" that BT's activities, including its major investment in super-fast broadband, are delivering for London.
He said the firm plays "a vital role" in the prosperity and well-being of this capital city, with BT being one of the few businesses to have a people presence in every borough.
"BT's plans to roll-out next generation broadband across London are now at a very advanced stage," Mr Patel added.
"But we want to go further and would very much welcome the opportunity to have an even bigger impact on London's economy by working with the public sector to make the high-speed technology as widely available as possible."