More than 19 million people watched the then-18-year-old student from South Shields win the ITV talent competition. Since then his career has been a series of second chances.
Immediately after securing a £1 million contract with Simon Cowell's SYCO label, McElderry was faced with a reality-show backlash as social media roused itself to urge people to knock him from the Christmas number one slot, replaced by Rage Against The Machine.
However, after losing the slot that's near-guaranteed for X Factor winners, he bounced back to secure the New Year number one.
Then, following the release of his first album, Wide Awake, he was dropped by Cowell and looked set to slip into obscurity. Undeterred, McElderry was announced as a competitor on reality show Popstar to Operastar, which he went on to win last month.
That success led to a second record deal, this time with the classical arm of music industry giant Universal.
With his second album, Classic, due out on August 22, and a UK tour planned for November, life is looking up for the 20-year-old.
"Things are really good at the moment," McElderry said. "I love everything involved with my career – I love touring and promoting the album but the best thing is performing live.
"Everything I do, I do to make sure that I can keep performing live. Everyone at Decca has been really supportive of what I want to do and supportive of exactly how I wanted the new album to sound. It's a fresh start."
McElderry, who came out in July last year after previously denying he was gay, was famously the protegee of fellow Geordie Cheryl Cole. But now McElderry says he's had the good fortune to meet some of his music heroes and has been given their support.
"I've met Michael Buble, who was lovely, and I met George Michael. Elton John has been really lovely. He's such a great guy. I'm a huge fan of his so it was an honour to meet him," he said. "Elton checks in from time to time to make sure I'm OK."
It surely must be a pinch-yourself moment to have one of your idols calling up to see how you are – but McElderry sounds remarkably unfazed by all the attention.
With a growing fanbase he says his supporters are all "really lovely" and keep in touch by Twitter and Facebook. In fact, he said social media has ensured he knows a lot of his fans by name and that it's reassuring to look out into a crowd and see familiar faces.
His new album is launched just as the latest season of the X Factor starts. The show has courted its fair share of controversy this year with favourite judge Cheryl Cole moving to the US X Factor before being suddenly dumped by Cowell, and a new panel of judges taking over the British version.
This year's show will be judged by Louis Walsh, Gary Barlow, Kelly Rowland and Tulisa Contostavlos,
McElderry says the new panel will freshen up the show. "I'll be watching, definitely," he said. "I love the show. It's always exciting and this year is sure to be interesting."
Beyonce is one of his favourite stars, along with Adele, Lady Gaga and Jessie J. Interestingly, while his female influences are contemporary, his male favourites include Luther Vandross, Michael Jackson and, of course, Elton.
"I don't think there are that many good male singers at the moment," he added. "There's a gap in the market there."
As he waits for his second album to hit the shelves, McElderry must be hoping he's the man to fill that gap.
n Joe will be appearing at Hamilton Park Racecourse on Saturday, August 20.
