The eurozone's purchasing managers' index, compiled by research group Markit, rose to a 15-month high this month.
It indicates that the region is on the cusp of growth after months of contraction.
The figures will add to hopes that the worst of the economic downturn in Europe is over.
This initial estimate of the August figures is right on the boom-bust line of 50 points - a score below 50 indicates business contraction among the 16 nations that share the euro currency.
'The data are signalling that the unprecedented downturn has been followed by an historically rapid rebound that positions the eurozone to post growth ... in the third quarter,' said Rob Dobson, senior economist at Markit.
However 'rising job losses and the continued need for widespread and deep price discounting remain concerns looking ahead, as a sustained recovery in demand is necessary if the emerging rebound is to gain traction,' he added.
The separate PMI index for the eurozone's vast service sector also gained ground, up to another 15-month high of 49.5, a major rise from the 45.7 points posted in July.
The struggling manufacturing sector also saw an improvement, with its index rising to 47.9 from 46.3 in July.
The headline figure has improved in each of the past six months, after hitting a record low of 36.2 points in February.
August's jump of three points is the biggest since the survey began and significantly higher than the 48.3 point level predicted by analysts polled by Dow Jones Newswires.
'The outlook is becoming more positive, however, as the labour market retrenchment eased further in August, the inventory cycle remains supportive and confidence at service providers hit a 28-month high,' Mr Dobson said.
The survey results are the latest in a string of encouraging news for Europe's economy.
Last week, the EU's official Eurostat data agency announced that the eurozone's trade surplus doubled in June to €4.6bn.
Earlier this month, eurozone heavyweights Germany and France led a surprise rebound out of recession, helping drag the 16-nation eurozone very close to positive territory.
