Department for Transport data shows that eight million bus passenger journeys were made in the area in the year to March this year – down from 9.7 million in 2014-15, a 17% drop.
That means the average resident took 2.1 local bus journeys a month, compared to 2.5 in 2014-15 and the number of miles clocked by buses fell from 8.3 million to 6.7 million miles.
Nationally, there were 4.1 billion bus journeys taken in 2019-20, down 6% from 2018-19 and 12% from 2014-15.
The DfT says the number of journeys was impacted by Covid-19 restrictions but added the five-year trend did show there was "more that can be done to deliver reliable and regular bus services.”
In Northumberland, watchdog group Transport Focus carried out survey of bus users at the end of last year.
It found 87% of users were satisfied with local bus services, including 78% who were satisfied with punctuality and 61% with the price they were paying for fares.
The Campaign for Better Transport, a pressure group, said the annual statistics show route cuts and rising fares were “hitting communities hard, long before the pandemic".
Head of media Alice Ridley said: "Travelling by public transport must be affordable and convenient to avoid car journeys escalating and non-drivers being excluded."
The Government is currently drawing up a National Bus Strategy.
The DfT spokeswoman said: “This will build on our significant investment, which includes more than £900m of emergency funding to keep buses moving throughout the pandemic."