The growth in rent prices outside of London has reached 8%, the highest ever recorded figure by Hamptons.
However, rents in inner London have plummeted by 17.7%.
One reason for the rise in rents, the real estate firm says, is down to the lack of homes to rent.
Apparently, 300,000 fewer properties have come onto the rental market since the pandemic began in March last year.
And the figure is nearly a fifth lower than the year before.
The firm's head of research, Aneisha Beveridge, said: "We have seen a sharp decline this year in rental home numbers coming onto the market.
"Tenants are faced with less choice, which is pushing up rents."
Landlords can confidently increase the rent they want
She added that since growing numbers of landlords have several offers from tenants on the table, means they can confidently increase the rent they want.
The highest increase in rents was seen by tenants in the South East where prices rose by 10.6%. That's the first time that double-digit growth has been recorded in the region.
The average rent now being paid in inner London is £2,185.
Ms Beveridge said: "Rent stock levels have been compounded by the emergency legislation which sees a landlord extending their tenant’s notice period to a minimum of six months which reduces turnover further.
"There are signs this could change and over the past five months landlord purchases have begun to rise which will add to stock levels when these purchases complete."
The managing director of Accommodation for Students, Simon Thompson, said: "After a rocky year there is good news for landlords as rents are increasing but this will bring pressure on a tenant’s ability to pay.
"Fortunately, it appears there are more landlords investing in quality homes to rent and this will be a boost for the sector, especially for tenants."
The best BTL hotspots in London revealed
Meanwhile, one estate agency has revealed where in London the best buy to let investment hotspots are.
According to an analysis of rental yields by Portico, the best areas are in East London.
The firm says that there are still investment opportunities in the capital - if investors know where to look.
Top of their investment list is Barking, followed by Upney and then Wall End.
The firm's chief executive, Robert Nichols, said: "Our research shows there are healthy rental yields to be found in London and East London is still a BTL hotspot. We are also expecting tenant demand to increase as lockdown restrictions are eased."
