Last year, the portal says asking price rents rose 3% outside London but fell 4.4% inside the capital.
Rightmove is forecasting asking price rents to rise 4% outside London this year.
The highest growth was recorded in the northern regions of Yorkshire & the Humber and the north-west; however, with the exception of London, all regions recorded a rise.
In inner London, rents fell by 5.2% while there was a smaller drop of 2.5% in outer London.
Rightmove’s head of lettings Sam Mitchell said of the 2017 market: “This year will be one of caution for buy-to-let investors due to tighter lending criteria and increased Stamp Duty.
“We definitely won’t see the spike in Q1 purchases that we saw last year as landlords rushed to buy before last April’s new Stamp Duty deadline.
“If the tax changes being phased in from this April lead to even fewer buy-to-let purchases and some landlords deciding to sell, then a tightening of supply in some areas will lead to increasing rents.
“We forecast that asking rents could rise by 4% outside London by the end of 2017, though in London prices are likely to stay flat.”
He added: “Investors looking for the strongest yields could consider investing in certain areas in the north-west where both demand and yields are high.
“Those with a number of properties in the capital may find that tenants are more price sensitive, so setting realistic rent levels will be the key to avoiding void periods.
“In order to mitigate this, we would recommend landlords asking for longer tenancies to help secure a steady rental income over the next few years while they adjust to what the tax changes will mean for them.”