A further 9% are planning to adopt the technology this year, according to the Quarterly Survey of Small Business in Britain by The Open University Business School, Barclays and ACCA.
In particular, the more entrepreneurial firms that want to grow even in the current economic climate are driving take-up, with some 65% of these firms using the innovative technology.
"Businesses are motivated by the ease, decreasing costs and the exceptional increase in power we're seeing in handsets," said Steve Cooper, managing director of Barclays Business.
"We've reached a point where smartphones are running many of the applications that once needed a decently powered laptop. Businesses can log-on, make payments, send through an invoice, do their word-processing and catch up on emails while standing at a patisserie in Lille.
"With around half of businesses already accepting or making payments over the internet, smartphone use looks set to accelerate the trend towards a cashless society."
The Open University Business School's Professor Colin Gray echoes Cooper's points: "These quarterly surveys over recent years have seen a strong trend towards the increased use of new ICT and online applications by growth-minded entrepreneurial firms. Britain needs to kick-start and sustain our economy on a longer term basis and technology could provide the answer."
The news comes amid a backdrop of slightly improved small business sales and employment figures. There has been an 8% rise in the number of transport and travel firms reporting an increase in sales over the past year while those in health and education increased by 2%. However, there were also some signs of inflationary pressures with more small firms having increased than having cut their selling prices over the past year.
Unsurprisingly, the economic climate and demand is the biggest problem currently cited by businesses [55% of business cited this in their top three], followed by cashflow and late payment issues [31%]. Despite these difficulties, many businesses are still advertising for business - in fact, while some 40% of all small firms do not advertise at all, of those that do well over half (57%) advertise online, presumably lured by the relatively low costs.
