It means landlords in the capital now have an average gap of £1,806 in rent received, compared to forecasts in 2016, buy-to-let lender Landbay calculated.
Rental price growth has remained in line with forecasts across the rest of the UK.
However, London’s property market has stalled since the Brexit vote, with rents rises of 1.26% in 2016 to lows of -0.33 in June 2017, according to the data.
There has been a partial recovery over the past 18 months, with growth rising to 0.58% in December 2018.
The average rent for a property in the UK, excluding London, increased by 1.16% in the year to December 2018.
The fastest rises are in the East and West Midlands, with increases of 2.19% and 1.48% respectively.
John Goodall, chief executive and founder of Landbay said: “It’s hard to ignore the impact that the vote to leave the EU has had on the property market in London.
“While tenants are better off, without necessarily realising it, uncertainty in the market has caused a conundrum for landlords.
“Many landlords will have been looking to offset the government’s punitive tax regime by raising rents, however the uncertainty surrounding Brexit has forced the vast majority to forfeit this to maintain a steady income.
“Brokers need to access the current landscape and provide insight to their clients on potential issues that may arise for them in the future. Despite a drop in rental growth the market continues to show resilience”