As speculation surrounds the couple, with many thinking they ARE married, Justin and Hailey decided to give fans something else to talk about, with Biebs serenading his girl outside of the Palace.
As the loved-up pair took a stroll through the city, Bieber whipped out his guitar and started to perform an acoustic version of his hit song 'Cold Water', with Hailey and an array of excited fans looking on.
One fan of the 24-year-old filmed the whole thing, posting the clip to his Instagram page for us all to enjoy. Alongside the video, the fan wrote, 'Justin Bieber singing in front of Buckingham Palace today! #shook #lucky #justinbieber #streetconcert'. sic
AMAZING! 🙌
Check out the biggest celebrity transformations below:
Swipe through to see the most amazing celebrity transformations of all time...
WATCH: Justin Bieber shocks fans by BUSKING outside of Buckingham Palace
2 of 33
Jonathan Tapper, now
But with the help of a diet plan, Jonathan was able to lose a whopping three stone in just 12 weeks, and six inches off his waist!
Swipe through to see the most amazing celebrity transformations of all time...
Little Mix, then
Perrie Edwards, Leigh-Anne Pinnock, Jesy Nelson and Jade Thirlwall looked very young in 2011 after winning The X Factor. To be fair, they were all teenagers at the time!
Little Mix, now
Now the biggest girl band on the planet, the girls look fantastic!
Calvin Harris, then
Scottish DJ Calvin Harris pictured here in 2009. Sorry Calvin, but we're not sure that look would be Acceptable In The 80s - OR now.
Calvin Harris, now
The 'One Kiss' hit-maker transformed into an A-list hunk, and has dated the likes of Taylor Swift and Rita Ora. Twit twoo!
Cheryl, then
Girls Aloud singer Cheryl was just a fresh-faced teenager when she auditioned for Popstars: The Rivals in 2002.
Cheryl, now
She's now an on-trend and super-glamorous mum-of-one, even walking the red carpet at a London Fashion Week show.
Justin Bieber, then
Little Justin Bieber was just a Baby when he burst onto the scene in 2009...
Justin Bieber, now
These days, he's of course grown up - but he looks pretty much the same! Apart from the fact that he no longer has the signature Bieber hairstyle, of course.
Rihanna, then
A young Rihanna in 2005...
Rihanna, now
The still cheeky Fenty grin is still there, and Rihanna continues to defy the aging process.
Matthew Lewis, then
Harry Potter star Matthew Lewis starred in the film series as Neville Longbottom from 2001 to the last film in 2011, here pictured in 2004 at the Harry Potter and the Prisoner of Azkaban premiere.
Matthew Lewis, now
Matthew grew up into such a good-looking chap that the makeup department on the Potter films had to try and make him less attractive in the later films, even spawning the phrase 'Longbottomed'.
Miley Cyrus, then
Miley Cyrus in her Hannah Montana days...
Miley Cyrus, now
She may have gone through various transformations, but Miley is still recognisable.
Gareth Gates, then
Pop Idol contestant Gareth Gates on the show back in 2001...
Gareth Gates, now
Here in 2017, he showing off his muscular physique alongside his girlfriend Faye Brookes.
Katy Perry, then
Katy Perry rocking long black hair in 2004...
Katy Perry, now
And showing off her shorter, blonde pixie cut in 2017.
Chris Pratt, then
Jurassic Park actor Chris Pratt back in 2008...
Chris Pratt, now
Shed the pounds and now has a slimmer physique.
Kylie Jenner, then
A fresh faced Kylie Jenner in 2008...
Kylie Jenner, now
Now rocking a platinum blonde 'do at the age of 21 in November 2018.
Zac Efron, then
Zac Efron in his High School Musical days back in 2007...
Zac Efron
10 years later, he was looking incredibly dapper at the Australian premiere for The Greatest Showman in 2017 - even sporting a 'tache.
Justin Timberlake, then
JT rocking his epic tight curls with frosted tips back in 2000...
Justin Timberlake, now
He's so much more grown-up in September 2018 whilst performing in Las Vegas.
Johnny Vegas, then
TV personality Johnny Vegas, real name Michael Pennington, is well known for his larger frame.
Johnny Vegas, now
But in 2018, he revealed that he'd lost two stone.
Jack Ryder, then
Jack Ryder, AKA Jamie Mitchell from EastEnders, was a noughties heartthrob if ever there was one.
Jack Ryder, now
In 2018, Jack was announced to be joining Holby City - and look at him now!
Jonathan Tapper, then
Gogglebox's Jonathan Tapper was 21st 3lbs at his heaviest whilst appearing on the show with his family - wife Nikki, daughter Amy and son Josh.
Jonathan Tapper, now
But with the help of a diet plan, Jonathan was able to lose a whopping three stone in just 12 weeks, and six inches off his waist!
Swipe through to see the most amazing celebrity transformations of all time...
Little Mix, then
Perrie Edwards, Leigh-Anne Pinnock, Jesy Nelson and Jade Thirlwall looked very young in 2011 after winning The X Factor. To be fair, they were all teenagers at the time!
Little Mix, now
Now the biggest girl band on the planet, the girls look fantastic!
Calvin Harris, then
Scottish DJ Calvin Harris pictured here in 2009. Sorry Calvin, but we're not sure that look would be Acceptable In The 80s - OR now.
Calvin Harris, now
The 'One Kiss' hit-maker transformed into an A-list hunk, and has dated the likes of Taylor Swift and Rita Ora. Twit twoo!
Cheryl, then
Girls Aloud singer Cheryl was just a fresh-faced teenager when she auditioned for Popstars: The Rivals in 2002.
Cheryl, now
She's now an on-trend and super-glamorous mum-of-one, even walking the red carpet at a London Fashion Week show.
Justin Bieber, then
Little Justin Bieber was just a Baby when he burst onto the scene in 2009...
Justin Bieber, now
These days, he's of course grown up - but he looks pretty much the same! Apart from the fact that he no longer has the signature Bieber hairstyle, of course.
Rihanna, then
A young Rihanna in 2005...
Rihanna, now
The still cheeky Fenty grin is still there, and Rihanna continues to defy the aging process.
Matthew Lewis, then
Harry Potter star Matthew Lewis starred in the film series as Neville Longbottom from 2001 to the last film in 2011, here pictured in 2004 at the Harry Potter and the Prisoner of Azkaban premiere.
Matthew Lewis, now
Matthew grew up into such a good-looking chap that the makeup department on the Potter films had to try and make him less attractive in the later films, even spawning the phrase 'Longbottomed'.
Miley Cyrus, then
Miley Cyrus in her Hannah Montana days...
Miley Cyrus, now
She may have gone through various transformations, but Miley is still recognisable.
Gareth Gates, then
Pop Idol contestant Gareth Gates on the show back in 2001...
Gareth Gates, now
Here in 2017, he showing off his muscular physique alongside his girlfriend Faye Brookes.
Katy Perry, then
Katy Perry rocking long black hair in 2004...
Katy Perry, now
And showing off her shorter, blonde pixie cut in 2017.
Chris Pratt, then
Jurassic Park actor Chris Pratt back in 2008...
Chris Pratt, now
Shed the pounds and now has a slimmer physique.
Kylie Jenner, then
A fresh faced Kylie Jenner in 2008...
Kylie Jenner, now
Now rocking a platinum blonde 'do at the age of 21 in November 2018.
Zac Efron, then
Zac Efron in his High School Musical days back in 2007...
Zac Efron
10 years later, he was looking incredibly dapper at the Australian premiere for The Greatest Showman in 2017 - even sporting a 'tache.
Justin Timberlake, then
JT rocking his epic tight curls with frosted tips back in 2000...
Justin Timberlake, now
He's so much more grown-up in September 2018 whilst performing in Las Vegas.
Johnny Vegas, then
TV personality Johnny Vegas, real name Michael Pennington, is well known for his larger frame.
Johnny Vegas, now
But in 2018, he revealed that he'd lost two stone.
Jack Ryder, then
Jack Ryder, AKA Jamie Mitchell from EastEnders, was a noughties heartthrob if ever there was one.
Jack Ryder, now
In 2018, Jack was announced to be joining Holby City - and look at him now!
Jonathan Tapper, then
Gogglebox's Jonathan Tapper was 21st 3lbs at his heaviest whilst appearing on the show with his family - wife Nikki, daughter Amy and son Josh.
Jonathan Tapper, now
But with the help of a diet plan, Jonathan was able to lose a whopping three stone in just 12 weeks, and six inches off his waist!
Despite earlier reports saying the couple weren't going to 'rush' anything, Justin and Hailey were spotted at a courthouse in New York City - a courthouse which is well known for issuing marriage licences.
With everybody thinking they'd tied the knot, Hailey took to Twitter in a now deleted tweet to write, ‘I understand where the speculation is coming from, but I’m not married yet!’
HOWEVER, since then, Hailey's uncle, actor Alec Baldwin, spoke to the press and said, "They just went off and got married and I don't know what the deal is".
WE NEED ANSWERS! 👀
You can hear Justin's biggest hits on the MFR playlist.
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