Last night Justin Bieber saw in his 21st birthday with a showbiz bash worthy of one of the world's biggest singing stars. The Champagne flowed, he took selfies for his 21.3 million Instagram followers that included his rumoured girlfriend Hailey Baldwin, and tweeted to his 61 million Twitter followers, 'Grateful to be alive!!! Love u!!! 21' And the Ontario-born heartthrob has much to celebrate - not only has he been a pop sensation for eight years but recent behaviour that seems to suggest he's put his rocky teen years behind him to embrace a calmer, more reflective adulthood. As Justin turns 21 today, we take a look back at his ups and downs over the years - from his very first single and THAT iconic haircut to his brushes with the law and attempt at a comeback . Yet, the rapidly maturing Justin celebrating his birthday today, with estimated wealth of $200million (£130milllion) is very different to the angel-faced teen who sang his heart out as a 13-year-old on YouTube. Born in Ontario, Canada, and brought up by a single mother Patricia or Pattie Mallette, he was discovered by accident after she posted a video of her son singing Ne-Yo's So Sick at a school singing competition on YouTube for their friends and family to see. She added more videos of Justin singing various R 'n' B covers until one day, music executive Scooter Braun, who worked with Ariana Grande, Psy and Carly Rae Jepsen, was searching for another singer and stumbled on his homemade performances. So impressed, he located Justin's school and tracked down Pattie and persuaded her to let him work with her son. At the age of 13, Justin traveled to Atlanta, Georgia, with Braun to record a demo tape and one week later he was singing for Usher. Justin signed a recording contract with the famous L.A. Reid and released his debut EP, My World, in November 2009 which went platinum in North America. Justin poses with a fan on the Ellen DeGeneres show on February 19 . Last month, it was revealed that Justin will be the subject of a roast on Comedy Central - a sign that he may finally be ready to stop taking himself so seriously. Pictured: A still from the roast . Justin has a target 'tattooed' on his back to symbolise he will be the target of jokes for the night . TV appearances followed including a performance for President Barack Obama and the first family at the White House  and in 2010 he joined the remake of We Are The World to raise money for Haiti, singing the opening line - originally sung by Lionel Richie. Meanwhile Justin was  gaining a devoted following of Beliebers, girls who express their devotion to their idol on social media and travel the world following his every move. Even going through puberty couldn't change their devotion and Justin talked openly about having a deeper voice in his second album and remarked: 'It cracks. Like every teenage boy, I'm dealing with it and have the best vocal coach in the world.' Justin launched into fame in 2010 with the help of his mentor Usher (left) and talent manager Scooter Braun (right) He released his debut EP, My World, in November 2009. The album went platinum in the U.S attained double platinum recognition in the UK . Since then, Justin has become a wildly successful international superstar, with millions of devoted fans who call themselves 'Beliebers' The teen sensation began breaking into acting, playing a troubled teen in CSI: Crime Scene Investigation in September, 2010, . His third album Believe, which came out in 2012, marked a different musical direction. Meanwhile, Justin may have been known for his angelic smile and saccharine lyrics, he started to earn himself something of a bad boy reputation. In 2013, at the age of 19, a video was leaked that appeared to show Justin urinating into a mop bucket and launching into a bizarre verbal attack on Bill Clinton. And while his 21st birthday today marks his status as a legal adult in the US., Justin has been indulging in adult pleasures since he was a teen. Fans are pictured in London waiting for him to arrive at the premiere of his 2011 movie Never Say Never . Justin throws his coat into the crowd as he performs at the 2010 Much Music Video Awards in Toronto . From 2010 to 2013,  Justin maintained an on-and-off relationship with singer Selena Gomez - but it seems even she couldn't keep up with his unpredictable behaviour . In January 2014, he was arrested in Miami Beach, Florida, on suspicion of driving under the influence and drag racing, reaching an eye-watering 136mph in his rented Lamborghini. He was ultimately charged with driving under the influence, resisting arrest and driving with an expired license. Just days later, Justin was accused of assaulting a limo driver in December 2013. The charges were later dropped. And that summer, in July, the controversial pop star faced a misdemeanour vandalism charge for egging his neighbour's home - an incident that resulted in the neighbour taking out a restraining order against him. In 2011, Justin got rid of his iconic bowl-style haircut and began to add more street style to his look . Justin Bieber in low-crotch white trousers performs live on stage at 02 Arena in March  2013 in London . Throughout all the drama, Justin maintained an on-and-off relationship with singer Selena Gomez - but it seems even she couldn't keep up with his unpredictable behaviour. The pair officially broke up in 2013, and now she is dating DJ Zedd. Clean-cut Selena, 22, has remained tight-lipped about their time together but she recently admitted in an interview on Norway's NJR radio: 'I definitely have so much respect and love for him,' She said: 'And he has heard [the song] and he has seen the video, and it's something that I feel like girls need hear, and it's something I'm willing to share with people. She admitted her single The Heart Wants What The Heart Wants is about him. 'He thought it was beautiful [but] I think it is really hard at first.' She added: 'I support him, I think I always will. I'm upset when he is upset, I'm happy when he's happy. I don't want anything to every happen to him, it hurts me.' In January 2014, he was arrested in Miami Beach, Florida, on suspicion of driving under the influence and drag racing, reaching an eye-watering 136mph in his rented Lamborghini . Justin is pictured playing basketball with Chris Brown, who is infamous for his violent behaviour . Justin shared a picture of a private jet he chartered for a trip in December 2014 . Yet as the world seemed to tire of his antics, early this year Justin began making an effort to turn over a new leaf and win back his fans. His new career moves seemed designed to introduce to the world a new, mature Justin - someone who didn't mind laughing at himself and who might want to be more than a teen idol. First in January, he made his debut as a ripped, muscled underwear model for Calvin Klein showing off a six-pack and copious tattoos and in a pair of tight white briefs. The campaign made such an impact that Calvin Klein has amassed more than 3.6million followers across its social media channels ever since the photos were released. He appeared on The Ellen DeGeneres Show, which aired on January 29 with a new blonde hairdo and a humble attitude. 'Honestly I haven’t been on TV in a while so I’m a little nervous,' he admitted. The singer has long been close to his mother Patty Mallette, who was 17 when she had him. Pictured: The pair in May 2014 at a basketball game . Justin Bieber strips down onstage at Fashion Rocks 2014 in September in New York City . Justin opened up about his troubled past and how he has a positive outlook for the future. They also touched on the Comedy Central Roast airing on March 30 on the US cable channel, a brutal hour in which comedians write and perform eye-wateringly close-to-the-bone jokes about the celebrity subject. Both Pamela Anderson and Michael Hasselhoff have been good natured victims of the televised ritual. The event, which will be hosted by Kevin Hart, apparently was put together entirely on Justin's urging. A source at the network told Ryan Seacrest's website: 'Justin has been asking us for years to roast him, so we kept telling him to create some more material and we're thrilled he listened.' Justin told Ellen: 'I think it’s just cool to be able to laugh at yourself so. I’ve done some things. That might not of been the greatest. 'I just want to be able to ya know. And kind of just kind own up to some of the things.' In September, Justin was seen hanging out with models-of-the-moment Gigi Hadid and Kendall Jenner . Indeed, after the interview was taped, Justin posted a video online to apologize for his behavior over the past year and a half. He  said in the video  that he doesn't want to appear 'arrogant or conceited or basically how I've been acting the past year, year and a half... I'm not who I was pretending to be.' He added: 'Often, we pretend to be something we're not as a cover up of what we're truly feeling inside. And... just being young and growing up in this business is hard.' The star made another appearance on the show on February 20, showing talking about his new role in the ABC show Repeat After Me and then posing for pictures with one of his fans Jacqueline Melanson, from Boston, who was ecstatic to pose for pictures with her idol. He is also seemingly making an effort to downsize his lifestyle. Last week it was revealed that he has moved from a $60,000 (£40,000)-a-month mansion to a $35,000 (£22,700)-a-month house in Beverly Hills. With a new girlfriend, a sophisticated new celebrity clique that includes Kendall Jenner and Gigi Hadid, more acting roles in the pipeline, it's clear the man famous for his hit Baby is ready to be grown up.
Justin Bieber, who turns 21 today, has been a superstar for eight years . Has millions of fans, multiple arrests and a reputation as a bad boy . Wants to revitalise his career again and has apologized for behaviour . Hopes to laugh at himself on Comedy Central 'roast' set to air on March 30 . Also has a rumoured new girlfriend and downsized his home .