Over a million of pensioner households in the UK now have a total wealth of more than £1m, according to analysis by Prudential.
The retirement company said this growth in wealth was down to a boost in the average value of pension assets, an increase in the value of savings and investments held by retired households and a rise in property values.
Examining Office for National Statistics data for 2010 to 2012, Prudential found that the number of millionaire pensioner households increased by 69% compared with 2006 to 2008 when the number stood at just over 636,000.
This means that more than one in ten (11%) of over-65 households in 2010/12 had a total wealth of over £1m.
Prudential retirement expert Vince Smith-Hughes said: 'These results challenge a few commonly held perceptions.
'The figures underline the importance of people saving as much as possible as early as possible in their working lives to enable then to secure a comfortable income in retirement.
'Even those who will fall into the growing number of pensioner millionaires when they retire need to consider their income options.'
Prudential said that the average value of private pension assets increased to £82,300 in 2010/12, up from £60,000 in 2006/06. The number of people who have private pension wealth in this period grew to 76% from 73%.
Less than one fifth (19%) of over-65 households now have savings and investments worth more than £100,000 - an increase from 15% in 2006/08.
The average net property value for a retired couple is £210,000, up from £200,000 in 2006/08.
At the other end of the spectrum, Prudential's analysis also shows that 12% of pensioners households are worth less than £40,000.