Some 40% of private tenants are aged over 46, according to a study by Your Move.
The agency researched 36,500 tenants and found a high proportion of 'silver renters'.
Almost a fifth (18%) of tenants were aged over 55 and 22% were aged between 46 and 55.
Your Move says that just 39% of the tenants in its sample were under 35.
The study also questioned the tenants' attitudes towards renting.
Nearly half of the tenants surveyed aged 55 and above said they were satisfied with renting.
Meanwhile, 25% of 18-25 year-olds said they were happy being a tenant.
Across all age groups, 81% of tenants said that renting suited their current lifestyle.
"The rise of the Silver Renter may seem surprising, but increasingly thousands of people have turned to the Private Rental Sector as the most convenient option available to them, following a change in personal circumstance," says Valerie Bannister, head of lettings at Your Move.
"Now more than ever, it is important that this sector offers good quality, well managed properties that allow tenants to feel at home in them."
“The Private Rental Sector needs to [become] a first choice tenure, and not just the second best option."
"If the flexibility of renting can be combined with the stability and reassurance of longer residencies, and fewer restrictions around making the space ‘feel like home’, for many, renting would be considered a better long-term, as well as short-term, option,” she adds.