Border collies Chess and Cookie, Staffordshire Bull Terrier Mr Biggs and Mr Duke, a 10-year-old Spaniel cross were finally whisked away after they spent a total of 1,556 days at the rehoming centre in Harvil Road.
Four-month-old Chess will now be trained to save the life of his new owner Tamara Simeunovic, who suffers from epilepsy.
She said: “Chess has already settled in really well – he is a lovely addition to our family, and he's even made best friends with our pet budgie.
“We plan to take Chess to Dogs Trust Harefield's Dog School puppy classes, and then on to seizure alert classes when he is an adult.
“Eventually Chess will help detect my epileptic seizures, which will make a huge difference to my life and safety.”
Dogs Trust Harefield rehomed 600 dogs in 2016.
The animal welfare charity care for and find new homes for dogs that have been abandoned or given up by their owners.
There are 20 centres across the UK, including the Harefield centre.
Rehoming centre manager at Harefield, Richard Moore, said: “We are so pleased to see that Cookie, Chess and Mr Biggs have all found their special someone and have got the new year off to cracking start – especially given that they had been with us for such a long time.
“We know they'll be very happy with their new owners.
“We're equally delighted for Chess – he'll have such a positive impact on his owner's wellbeing.”
Keep up to date with the latest news in west London via the free getwestlondon app.
You can even set it to receive push notifications for all the breaking news in your area.