Everything Everywhere – the company behind Orange and T-Mobile – has been given the go-ahead to offer so-called 4G services from 11 September.
It has been trialling 4G services in Cumbria since early summer. Other companies could start delivering 4G services from next year.
Telecoms watchdog Ofcom said the decision would deliver "significant benefits" to consumers that outweighed any competition concerns.
"Delaying doing so would therefore be to the detriment of consumers," Ofcom said.
Allowing Everything Everywhere to reuse its spectrum in this way was likely to bring material benefits to consumers, including faster mobile broadband speeds.
Depending on how Everything Everywhere used the technology, it could also deliver wider mobile broadband coverage in rural areas.
NFU chief rural affairs adviser David Collier said that it was clear that farmers and rural businesses had high expectations of 4G mobile broadband.
"Farmers expect multiple benefits from 4G mobile broadband," added Mr Collier. "They expect to be able to use the internet more and use it more effectively.
"From doing business with their customers or seeking out new suppliers to doing administrative work such as banking, invoicing or completing online forms, the internet has become a vital component of rural life.
The findings are taken from the results of the annual NFU communications survey.
"Those in areas where the current landline connection is painfully slow are looking forward to using the internet much more easily and effectively than before."
BT Wholesale and Everything Everywhere have already devised what they claim is an innovative new way to use 4G to extend faster broadband to rural areas.
The solution uses next-generation 4G Long Term Evolution (LTE) technology that can reach download speeds of more than 100 megabits per second.
An initial test was undertaken at BT's laboratories at Adastral Park in Suffolk last year, with a field trial in Cornwall later testing 4G broadband data speeds outside laboratory conditions.
The trial started a year ago and was extended early this year.
It involved up to 100 mobile and 100 fixed line customers living around the St Newlyn East area of South Newquay, Cornwall.