The number of properties available to rent per member branch fell to an average of just 11 in August.
At the same time, 197 potential tenants registered, compared to 149 in July 2022.
Nathan Emerson, chief executive of Propertymark, said: "Governments across the UK have shown little urgency in addressing supply and demand by incentivising landlords to invest.
We continue to see this gap widen as more and more people enter the market in search of housing and few properties are available to rent.
This continues to put pressure on rents as 68 per cent of our member branches saw rents increase compared to the previous month.
The sales market is following a different trend, with the supply of sales increasing by 29 per cent to 45 units per branch in August.
The average number of new prospective buyers registered per member branch rose from 64 in July 2023 to an average of 81 in August.