A total of one in 10 70-74 year-olds in Britain is now in employment - almost double the number a decade ago.
It is the highest figure since comparable records began in 1984.
Just over a quarter of million 70-74 year-olds in Britain are currently employed, according to new statistics from the Department for Work and Pensions (DWP).
This is up from 123,000 in 2005 and around 100,000 at the start of the century.
The jump is part of a broader rise in the number of people aged 50 and over who are holding jobs.
The DWP said that part of the increase can be explained by demographic changes, but that growth in employment rates show that the number of people over 50 in work is rising faster than the size of the over-50 population.
Responding to the figures, Paul Kenny, GMB General Secretary, said: "The trend for people to live longer has coincided with the cutting back by private sector employers of pensions for retired staff.
"Good pensions have been replaced by glorified saving schemes that deliver not much in the way of pensions.
"Try living on the basic state pension of less than £116 per per week."
The figures also show that around one in seven men of state pension age (65 and over) are currently in employment, up from one in 11 a decade ago.
A slightly lower number of women of pension age have jobs: roughly one in 14, up from one in 23 in 2005.
TUC General Secretary Frances O'Grady said: "The last decade has seen profound changes in the labour market, with far more people working beyond retirement age. While there are plenty who enjoy remaining in work, many need to earn extra cash because they cannot afford to retire.
"We need decent jobs and pensions for all so that people can make a genuine choice about whether they remain in work and can access quality employment opportunities which make good use of their skills and experience."
John Allan, Federation of Small Businesses chairman, said: "More and more older people are opting for a career change later in life and are starting up their own businesses, pursuing something they may have dreamed of doing for years.
"It's vital that older business entrepreneurs and start-ups get the right support and finance they need to grow and create future jobs."
A spokesman for the Department of Work and Pensions said: "We know many people want to stay in work longer, which is why we ended the discriminatory default retirement age.
"People are now able to choose how long they stay in work and that's a good thing.
"Ensuring that pensioners have a decent income in retirement is a top priority and that's why we brought in the triple lock for today's pensioners while future pensioners will benefit from automatic enrolment and the new state pension."