Biffy Clyro, Calvin Harris and Arctic Monkeys will headline the three-day event, with other big names in the line-up including Paolo Nutini, Ed Sheeran and Jake Bugg.
Pharrell Williams, Ellie Goulding and Elbow will also perform in front of a daily crowd of up to 85,00 music fans who are marking the end of an era at Balado airfield in Kinross, which has been the festival’s home for the past 18 years.
Organisers have called this year’s event a “huge send-off party” as the festival will be held at Strathallan Castle estate in Perthshire next year.
The campsite gates opened last night with crowds turning up early to grab the best spot for the festival which is celebrating its 21st year.
Other performers over the weekend include the headliners of T in the Park’s first year at Balado - The Charlatans and Paul Weller - with both acts taking to the stage 18 years to the day after they performed at the festival’s debut in Kinross.
Festival director Geoff Ellis said: “This weekend, we mark the end of an era. The Balado site has never looked more beautiful, and we’re getting ready to give our much-loved home for the past 18 years the incredible send-off it deserves.
“We’re really looking forward to celebrating one last time here with the greatest audience in the world, and can’t wait to welcome you all as we throw Balado a farewell party.”
More than 2,800 artists have played Balado over nearly two decades, including Foo Fighters, The Stone Roses, Rihanna, The Killers, The Who, Daft Punk, Kylie Minogue, Oasis, Beyonce and Eminem.
Biffy Clyro have played the most times, with their main stage headline set tonight taking their total performances there to 10.