Taking to Instagram on Tuesday, the 61-year-old shared a sweet picture of their pet Labrador, Jacob, wearing a vibrant orange jacket emblazoned with the slogan: "I do tricks for treats."
Their furry friend melted hearts in the snapshot as he turned his head towards the camera whilst sitting obediently outside what appeared to be their family home.
In his caption, David shared a personal message from the entire family which read: "Happy Hallowe'en from the Furnish-John family [pumpkin and ghost emoji] @eltonjohn."
Awestruck fans couldn't contain their enthusiasm in the comments section. One follower sweetly penned: "Jacob dressed up! I hope he gets some treats and no nasty tricks this evening," while another remarked: "Puppy eyes say it all! [smiley emoji with love hearts] Happy Halloween!"
A third noted: "Happy Halloween to you all. Love your doggie's coat," and a fourth chimed in: "Omg too cute for words."
Aside from Jacob, whom they adopted as a puppy, David, Elton and their two children are proud pet parents to two additional sweet pups.
Back in July, David announced the arrival of two family additions in the form of French bulldogs Regine and Nicole.
At the time, the father-of-two wrote a caption which read: "Here we grow again. Meet the two newest additions to the Furnish-John family - Regine and Nicole."
Besotted fans flocked to the comments section with an abundance of sweet messages. "They are the sweetest cuddliest pups!" noted one, while a second commented: "Those babies are getting large! And have grown very quickly."
A third wrote: "So totally gorgeous, wishing you endless happy days together," and a fourth added: "So sweet and the names are equally fitting!!!"
Sir Elton and David, who tied the knot in 2014, welcomed their first son Zachary Jackson Levon Furnish-John via a surrogate in December 2010.
The couple opted for surrogacy in accordance with the Center for Surrogate Parenting in Encino, California.
According to MailOnline, the couple reportedly paid the surrogate, whose identity has been kept hidden, a lump sum for giving birth to their firstborn, and just three years later, the couple used the same surrogate to welcome their second son, Elijah.
Shortly after welcoming their second son, Sir Elton shared a statement which read: "Both of us have longed to have children, but the reality that we now have two sons is almost unbelievable."
Meanwhile, in 2016, the 'Cold Heart' singer shared a sneak peek inside his fatherhood journey during an interview on the Today Show. Opening up, he shared: "That was the greatest decision I've made — well — we've made, in the last six years, is to have those boys… Our primary concern. They're the things that come first and foremost."