The Equality Trust charity compared the £5.3m average pay of a FTSE 100 chief executive with the £13,660 earned by someone on the living wage.
The findings come as the government prepares to publish the findings of its consultation on corporate pay.
One proposal suggested forcing firms to reveal the pay gap between their chief executives and average workers.
The government's green paper on corporate governance was opened to public consultation in November.
Other suggestions aimed at curbing corporate pay included improving the effectiveness of remuneration committees and the extent to which they must consult shareholders and workers on executive pay levels.
The Equality Trust, which was set up in 2009 and aims to reduce economic inequality, examined the 2015 annual reports of FTSE 100 companies.
It found that more than two thirds of chief executives were paid in excess of 100 times the average UK salary of £27,615. Only six of the bosses were paid less than £1m in that year.
The charity found the company with the biggest pay gap was WPP. Its chief executive, Sir Martin Sorrell, earned £70m in pay, bonuses and share plans in 2015 - 5,154 times more than someone on the living wage and 2,550 times higher than those on the UK average wage.
One third of investors in WPP - the world's largest advertising group - failed to back Sir Martin's pay package at its annual meeting.
He defended the package saying his pay was based on the performance of WPP - .
Responding to the Equality Trust survey, a WPP spokesman said Sir Martin's package "reflected WPP's strong outperformance of both its comparator group and the FTSE 100 over the five-year period ended December 2015".
Other firms found to have a big gap between pay for chief executives and average workers were Reckitt Benckiser, Sky and Shire.
The Equality Trust said: "Too often, bosses are treated as untouchable talent to be retained at all costs, while millions of workers are seen merely as costs to be reduced."
It added that it was campaigning for mandatory pay ratio reporting to be introduced for all medium-sized and larger companies in a bid to help reduce levels of pay inequality in the UK.
The survey comes as Centrica's annual report reveals that chief executive Iain Conn enjoyed a near-40% rise in remuneration to £4.15m last year.
Most of the increase is due to a share award he was given when he joined the company in January 2015 from BP.
Bosses of the UK's 100 biggest firms earn 386 times more than workers on the National Living Wage, a survey found.