The latest data from the Office of National Statistics shows that the average property in the area sold for £145,233 – significantly lower than the UK average of £229,431.
Across the North East, property prices have fallen by 0.7% in the last year, to £127,885. The region underperformed compared to the UK as a whole, which saw the average property value increase by 1.2%.
The data comes from the House Price Index, which the ONS compiles using house sale information from the Land Registry, and the equivalent bodies in Scotland and Northern Ireland.
Northumberland saw the sixth-largest average price drop of any authority in the UK over the last 12 months, however the average homeowner will have seen their property jump in value by around £5,000 in the last five years.
The figures also showed that buyers who made their first step onto the property ladder in Northumberland in May spent an average of £118,486 – around £4,000 more than it would have cost them five years ago.
Residential research analyst at estate agent Savills, Lawrence Bowles, said: "The average UK house price rose by 1.2% in the year to May 2019, down from 1.5% in the year to April.
"London stands out this month as the nation’s worst performing region: prices there fell 4.4% compared to this time last year. The North East also saw prices fall 0.7% year-on-year, a reversal from annual growth last year of 1.4%.
"In every other region prices increased. The North West saw the strongest annual growth, followed by Wales and Scotland at 2.8%.
"With house prices lower relative to earnings, lower deposit requirements, and strong economic growth prospects, we would expect to see stronger growth in the North, particularly the North West, over the next few years."
Between April last year and March this year, the most recent 12 months for which sales volume data is available, 5,550 homes were sold in Northumberland, similar to the number in the previous year.
The highest house prices in the country in May were found in London's Kensington and Chelsea, where properties sold for an average of £1.25 million – 15 times the cost of a home in Burnley, where the average property cost just £86,000.