Figures by estate agent Haart showed the number of properties sold as rental homes in England and Wales fell 63.7 per cent in the year to November, while the number of landlords registering to buy homes was down 59.2 per cent.
Landlords have been hit with a succession of new rules in recent years, including an onerous three per cent hike to stamp duty, and a cap to the tax relief buy-to-let investors can claim on their mortgage interest payments.
In Philip Hammond's Autumn Statement last month, he insisted landlords, rather than tenants, should shoulder the burden of letting agents' fees.
The figures published today showed the number of homes sold in November fell to 47,279, down almost a quarter on last year, and 3.6 per cent lower than in October.
Average UK house prices fell 1.7 per cent to £228,635, according to the figures, while the average first-time buyers' home fell 5.9 per cent to £165,075.
However, prices in London rose 9.4 per cent to £582,909 - 6.2 per cent higher than in October.
Paul Smith, Haart's chief executive, hit out at the government.
"The scale of decline in buy to let in just twelve months is deeply worrying - landlords have clearly pulled out of the market and are unlikely to return any time soon.
"This is entirely the result of government policy, with Theresa May now picking up George Osborne’s baton and proceeding to bash landlords with renewed vigour.
"The government’s attack on investors adds up to a ‘War on Landlords’ and a buy to let market crippled by tax hikes and unnecessary regulation. The effect has been to more than halve the number of buy to let sales in England and Wales, and the inevitable consequence will be fewer properties available to renters next year and higher rents."