According to the online estate agent, there are about 20,000 properties for sale in excess of £1m in the UK, and a third of these are in five London boroughs.
More than three quarters of all properties for sale in excess of £1m are in London and the Home Counties.
The City of Westminster, Kensington and Chelsea, Camden, Wandsworth, and Southwark have almost 7,000 properties on sale for more than £1m.
In areas surrounding the capital, Surrey has almost 2,000 high-end properties for sale, While Hertfordshire has 700 currently on the market.
In the North, Cheshire, Greater Manchester, and North Yorkshire have the highest number of £1m properties for sale, while Edinburgh and Pembrokeshire claim the highest number in Scotland and Wales.
High end London property has struggled since the Brexit referendum of 2016, with house prices dropping and sales dwindling.
Sam Mitchell, CEO of Housesimple, said: "Although Brexit has loomed large over house prices in London recently, the capital remains a global city with property values to match.
"But for buyers who are lucky enough to have a budget of £1m plus, this is the market where you could negotiate a healthy discount.
"By looking beyond London and the South East, wealthy buyers can maximise on space and special features, especially those looking to move from the city to the countryside.
"However, the ongoing north/south divide means prices are still rising in counties like Yorkshire, so bargains in traditionally affluent areas such as Harrogate will be harder to come by."
Greg Cunnington, director of lender relationships and new homes at Alexander Hall, said: "Despite the slowdown in London property values that have been seen there is we are still seeing real demand from buyers across all demographics on the purchase front, and so the research from Housesimple here is no surprise.
"The five London boroughs are all seen as ideal hot spots combining quality of life with location and good schooling, along with the low levels of stock this means the values there will remain high.
"We are still seeing a lot of applications in these traditional prime areas of London.
"We are also seeing a lot of clients looking to move to larger properties in the Home Counties. Where we have seen a shift is more investors are looking at holiday let properties, particularly in the south west, or looking for more yield outside of London."
Jonathan Harris, director of mortgage broker Anderson Harris, added: "Despite the drop in house prices in London, the capital is still where the greatest concentration of £1m-plus properties can be found.
"The good news for those looking to buy a property in this price bracket is that there may be a deal to be done as uncertainty over Brexit continues.
"Outside of London and the southeast, £1m will get you a lot more for your money. With resources and investment being directed away from London to regional cities in the UK, it is increasingly the case that if commuting to the capital for work is not as essential as in the past, you will still able to find some decent/relatively expensive housing stock."
