Osborne will make a speech in London today stating there are "tentative signs of a balanced, broad based and sustainable recovery". He is, however, expected to stress that it is still in the early stages and "plenty of risks" remain.
The Chancellor will say that recent months had "decisively ended" questions about his economic policy, according to reports.
Revised GDP figures showed the UK economy grew by 0.7% in the second quarter, with predictions growth could reach 1% in Q3.
Last week the OECD economic agency sharply increased its growth forecast for the UK economy this year, to 1.5% from an earlier estimate of 0.8%.
Osborne (pictured) is expected to say today: "The economic collapse was even worse than we thought. Repairing it will take even longer than we hoped. But we held our nerve when many told us to abandon our plan. And as a result, thanks to the efforts and sacrifices of the British people, Britain is turning a corner.
“In my view the last few months have decisively ended this controversy [about austerity]. Those in favour of a Plan B have lost the argument."
Labour dismissed the comments, saying Osborne was "trying to rewrite history".
"Three wasted years of flatlining under George Osborne have left ordinary families worse off and caused long-term damage to our economy," shadow Treasury minister Chris Leslie said.
"This desperate attempt to rewrite history will not wash when on every test he set himself, this chancellor's plan A has badly failed - on living standards, growth and the deficit."
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