The two-foot tall tree - bought for sixpence from Woolworths in 1920 - has now endured three monarchs, two global pandemics and a world war.
Kay Ashton, 66, who inherited the treasured family heirloom when her mother Joyce died in 2012, erected it earlier than usual this year because she was "fed up at home".
The artificial spruce, thought to be the oldest in the country, was bought by Kay's grandmother Elizabeth Naylor in 1920. The beloved tree survived Hitler's bombs during the second world war and has remained in the family for three generations and eight house moves.
But, according to Kay, perhaps most impressively of all it survived her late mother's habit for throwing things away. The tree, loving decorated in bells from Kay's childhood and lametta, takes pride of place in her kitchen in Sheffield.
Kay, a grandmother-of-three, says her grandmother would be "absolutely flabbergasted" to hear it was still going strong.
She said: "It's special that it has made it to 100 years. I don't now how - it was never really cared for, it was just always there. When my mum died, it was passed down to me. I was discussing what to do with it with my sister and I said 'I'll take it and I'll put it up'. I couldn't see it thrown in the bin.
"It's amazing it survived my mother to be honest, she was notorious for throwing things away. She threw my dad's medals away fro world war two, so it did well to survive her throwing it in the bin."
Elizabeth called it "William’s tree" to mark her new-born son’s first Christmas that year. William sadly died prematurely in 1940 aged 19 and the tree became a treasured family memorial to him.
Elizabeth - known as Nanan - died in 1981 aged 80 and the tree was inherited by her daughter, Joyce Ashton. When Joyce died in 2012, Kay became the third generation to own it.
Kay added: "It must be stronger than it looks. People say things were made to last in those days and this must have been. It's ever so light, I've put it up in the kitchen this year so that no breeze comes in and knocks it over.
"I never, ever put it up before December usually. It's usually the first weekend, around the 6th or 7th. But this year, I thought 'you're 100, you can come out of your box a bit early'.
"I was so bored and fed up at home, I thought it was something nice to cheer you up. It's become a joke really, every year it comes out and it looks a bit dodgy, but it makes people smile and even laugh out loud."
The tree incredibly survived a blitz of Sheffield's steelworks in December 1940 when the city was bombarded by the Luftwaffe for three consecutive nights.
Elizabeth kept the tree in the kitchen, but the impact of a bomb blast was so much that it blew it into the living room.
It was hit by shrapnel and sticky tape was used to repair it, which is still holding it together.
Kay added: "My sister says to me every year 'have you got that twig out yet?' and I say 'yep'. She says 'does it look any better' and I go 'nope'. I couldn't imagine not putting it up, it just brings back memories of Christmas and loved ones that we've lost.
"For me it's not about the tree itself, but about the history and its story. It was never the main tree, it still isn't. I have a bigger tree. But I always put this up. The only bells on it are from the 1920s or 50s, they're bells I remember from my childhood. It's like a link to the past, it is nice."
Kay, who retired from work last month, said her grandmother didn't speak much of the Spanish Flu pandemic, which ran from 1918 to 1920.
She added: "It's like it was the forgotten pandemic, its only recently people have been thinking about it with this pandemic that it is happening. But it was a lot worse than this one and killed a lot more people. My nanan had Bronchial Asthma, so she did well to survive it.
"She'd be absolutely flabbergasted to know it was still going."