Nearly one in seven people aged over 65 keep working to increase their income above their pension's level.
That is among findings by Metlife, which said its survey showed median additional earnings for working over-65s had reached £296 a week, while their savings and investment income was worth just £312 a year given low interest rates.
Average pensioner incomes were just 7% lower than average working age incomes, it noted.
It said the proportion of over-65s working had increased from 8% to 13% over the past decade, equivalent to 1.1m, though this was more common among pensioner couples, where 21% earned from working, against only 6% of single pensioners.
This trend was driven by the continuing squeeze on saving and investment income, and the proportion of pensioners earning money from investments had dropped from 72% in 2004-05 to around 64% now.
Simon Massey, wealth management director at MetLife UK said: "The rise in average pensioner incomes is a very welcome development which needs to be supported so future pensioners can look forward to similar or higher standards of living."
He said the increasing numbers who are working, contrasted with the slump in investment income, showed "the need for retirement savers and advisers to look at a range of solutions which can help ensure people have guaranteed incomes for life in retirement".