The baby boomers cast four million votes more than the younger millennials at the last general election - prompting fears of a “democratic imbalance”.
New research suggests the older generation’s large population and high turnout gave them a significant “ballot box advantage” against younger voters, who were a third less likely to vote.
The Resolution Foundation, which undertook the research, has called for more focus on addressing this generational gap, given the “profound implications” it could have on policy.
Laura Gardiner, senior research and policy analyst at the Resolution Foundation, said: “This poor turnout among young people is a deep-rooted problem, dating back to the mid-90s when young generation X-ers started turning away from the polling booth.
“This generational divide in turnout matters for our democracy, but also has profound implications for policy if politicians feel they only need to target the votes of older generations to win power.
“We need to explore ways to correct the democratic imbalance before the voting pool shrinks to a puddle.
“Ideas such as first-time compulsory voting with the option to not select any candidate, making voter registration easier, voting online and lowering the voting age are not silver bullets, but may help reverse this worrying trend.”
The research shows the turnout gap between the generations was just three percentage points in 1964.
But the gap between those in retirement (age 66-80) and those in early adulthood (age 21-35) reached 26 percentage points in 2005, and has remained close to that level ever since.
In last year’s election, 10.6 million baby boomers voted, around two-thirds of the generation’s population.
This compares with 6.4 million millennials, just 46% of those that could have voted.
The report also identifies a link between voting and home ownership, with those who own a home more likely to vote than renters across all generations.
It added that this may mean more millennials start voting as more get on the property ladder.
The research also found this drop off in voting coincides with growing disillusionment with political parties and the democratic process.
Back in 1992, 74% of millennials said they cared which party won the election. Last year the figure was 56%.
Over this same period, the share of those in retirement who care has risen slightly to 81%.
Millennials are defined as those born 1981-2000, generation X comprises those born 1966-1980, and the baby boomers are those born 1946-1965.