Some 38% of those taking part in Ipsos Mori's monthly political monitor picked Mr Balls as "most capable Chancellor", against 35% for Mr Osborne - a lead of three points. The pair were level-pegging the last time the question was asked in December.
It is the highest rating recorded for Mr Balls by Ipsos Mori since he became shadow chancellor in 2011, though he led Osborne by a wider eight-point margin in June last year.
The survey was conducted after high-profile speeches last week in which Mr Balls promised to maintain "iron discipline" on spending and Labour leader Ed Miliband said he would cap welfare.
But Mr Miliband does not appear to have won the same boost with voters, trailing David Cameron by 12 points - 37% to 25% - as the leader most trusted to deal with the economy, with Liberal Democrat Nick Clegg on 7% and Ukip's Nigel Farage on 6%. Mr Cameron was also most trusted to deal with welfare, on 30%, compared to Mr Miliband on 28%, Mr Clegg on 11% and Mr Farage on 7%.
The Conservatives led Labour by just two points - 38% to 36% - on being seen as most effective in getting good value for public money. Tories have led on this measure since 2008, and today's narrow margin is down from a highpoint of 11 in March 2010.
Overall, Ipsos Mori found Labour in the lead on voting intentions on 35% (up one point since last month), four points ahead of Tories on 31% (unchanged), Liberal Democrats on 10% (unchanged) and the UK Independence Party on 12% (down one).
Ukip's ratings were also down in a separate ICM Research poll for The Guardian, which put Mr Farage's party on 12%, down from an 18% spike during the council election period last month. ICM had Labour on 36%, Tories on 29% and Lib Dems on 12%.
Growing expectations of improvement in the UK's economic position were reflected in Ipsos Mori's Economic Optimism Index, which stood at zero, with equal numbers (31%) saying things would get better and would worsen over the next 12 months and 35% predicting them would stay the same. It was the first time since July 2010 that the index has not been negative.
Ipsos Mori head of political research Gideon Skinner said: "The economy is the top issue in the eyes of the public, but they have become more cautiously optimistic over the last few months. However, both of the main parties are still facing difficulties convincing voters that they have the right answers to get Britain out of the gloom"