Positive sentiment came from nearly half of small and medium sized businesses polled by CitySprint, with over two-thirds of respondents saying that they are either as confident or more confident about trading outlook as this time last year.
Only 14 per cent of Britain's small enterprise leaders felt that the Brexit vote would affect them significantly.
"It’s fantastic to see that the UK’s small businesses remain upbeat and ready to tackle whatever lies ahead. We know that they are resilient, having weathered the economic ups and downs over recent years," said CitySprint's chief executive Patrick Gallagher.
As for an exit timetable, the poll revealed most small businesses would like a six month delay before the clock starts on exit negotiations.
However, 20 per cent of businesses didn't see a need to wait and wanted the government to invoke Article 50 immediately.
London's small businesses did not feel quite so bullish though, with nearly three-quarters believing that there will be significant disruption to their operations.
Nevertheless, almost half (49 per cent) of the capital's business leaders were just as confident as the same time last year.
CitySprint encouraged smaller businesses to plan for the future. A third of respondents said that they "didn't know" how their business strategy and growth will be impacted.
"Business leaders must not become blasé about the future. As a business leader myself, I have been working closely with my leadership team to prepare for every likely eventuality,” said Gallagher.