Since its launch in 1999, the service has supported more than 80,000 quit attempts, contributing to record low levels of smokers in the county.
Currently, more than 90 per cent of Northumberland residents are non-smokers.
Research suggests that expert help makes smokers three times more likely to succeed in quitting.
Kerry Lynch, senior public health manager at Northumberland County Council, who helped set up the service, said: “We have seen a phenomenal amount of change over the past 25 years in the service itself, developing models to support people face to face, by telephone and providing online support via the website.”
Smoking prevalence in the county now stands at 8.2 per cent.
Gill O’Neill, Northumberland’s director of public health, said: “Just 17 years ago smoking in a restaurant or bar was legal.
“Thankfully legislation was introduced to protect workers in industries such as hospitality and public transport.
“The smokefree legislation was widely accepted and now we can’t imagine smoking being allowed on planes or in restaurants.”
Legislation this year aims to phase out the sale of tobacco products to anyone aged 15 or younger.