A survey found rooms yield in the Granite City last November fell year-on-year by 42.3% to Â£46.63 on average, while occupancy was down 11.9%.
It was the second successive monthly drop of more than 40% in revenue.
BDO said there was little sign of improvement on the horizon for Aberdeen hoteliers.
Across Scotland as a whole, hotel revenue fell by 9.5% and occupancy was down.
Inverness saw rooms yield rise by 5.1% while occupancy fell 1.6%. Edinburgh's revenue was up 0.1% but occupancy was down 1.4%.
Glasgow saw slight falls in both revenue and occupancy.
Alastair Rae, from BDO, said: "It is clear that Aberdeen hoteliers continue to be battered by the weak oil price and the consequent difficulties this is producing in the wider north east economy.
"Unfortunately there is little sign that will abate and the strain which the hospitality sector is currently experiencing is going to continue until something positive occurs in the oil and gas sector which appears unlikely in the coming months.
"The large falls in both revenue and occupancy in Aberdeen are also reducing the Scotland-wide figures for both as the other cities had a more positive month."
He added: "There are signs that the hotel sector is experiencing a stable, if unexceptional, year. Occupancy is relatively fixed and revenues are fluctuating slightly but not in a remarkable way.
"I believe that there will be more of the 'steady as she goes' outlook in the hotel market with the obvious exception being Aberdeen."
Room revenues have continued to plummet for Aberdeen hotels as weak oil prices batter the north east's economy, according to accountants BDO.