There should be a "fundamental re-appraisal" of government public health priorities, according to the Royal Society for the Prevention of Accidents (RoSPA).
A report by the charity says policies should focus on premature and preventable deaths.
On that basis, action to curb accidents should be the number one priority, it says.
Public health experts have welcomed the findings.
Official figures show accidents account for just 2% of deaths in England and Wales - far behind cancer, and heart and respiratory disease.
But RoSPA says this conceals the true impact of unintentional injuries.
Its report draws on data from the Office for National Statistics to argue for a new approach to public health.
The charity calculated the years of life lost as a result of premature death, based on the average number of years which those who died could have been expected to live.
This moved accidents up the priority list, because many victims die young.
RoSPA then filtered out deaths which could not have been prevented.
It found that up to the age of 60, accidents were the leading cause of preventable years of life lost, accounting for 23% of the total.
The charity's chief executive, Tom Mullarkey, says this is one of the most important findings in its 95-year history.
He says there is a "moral obligation" to prevent people dying before their time.
"We all know about diseases and the resources that are pumped into preventing the deaths they cause.
"But if only a fraction of that resource was used to prevent accidents we would not be faced, as we are today, with an accident epidemic that's wiping out people in their prime."
The charity says schemes to prevent accidents achieve quick results and can generate huge savings for the NHS.
It wants extra support and information for people at key moments in their lives - including teenagers, parents and carers of young children, and people over 65.
And RoSPA says that in England alone £1bn each year should be set aside to achieve this. The charity estimates that currently less than £1m is spent annually on these schemes.
In a statement, the Department of Health insisted that accident prevention was a key part of its approach to public health.
"We have introduced several ways to measure the effects of work to tackle A&E admissions due to accidents and the causes of accidents in general, including falls and fractures - many of which are preventable.
"For example, to reduce the number of falls and to help older people live independently after a fall, we are investing up to £300m into specialised housing over the next five years."