Jessie J revealed she felt "less than humble" as she headlined the 2013 iTunes festival.
The Price Tag singer, wearing white skintight hot pants and crop top, performed at the Roundhouse in Camden, on the day her second album Alive was released.
Watched by fellow Voice judge Will.i.am and Chipmunk, the 25-year-old was joined by US singer Brandy for a duet on new track Conquer The World. Dizzee Rascal, who is due to perform at the festival on September 27, also joined her on stage for Wild.
Jessie admitted: "This is a very special night for me, and a very special place for me to play my new songs. I feel very less than humble right now."
Opening with her number one single Price Tag, she performed material from her new album for the first time, as well as hits Nobody's Perfect, Laserlight, Do It Like A Dude and Domino.
Before launching into her latest single It's My Party, the former Voice judge told the crowd: "It's not very often I pay attention to the haters but a song lasts forever. So if you're at home watching this through your negative eyes, you're welcome to it!"
Jessie, whose real name is Jessica Cornish, brought some arena-style glamour to the intimate venue, with giant balloons, streamers and gold glitter falling from the ceiling throughout the set. British boyband Lawson was the opening act.
As she ended her performance with an emotional rendition of Alive, she declared: "I've finally realised what I want out of life, and I'm happy and content to be alive."
Blurred Lines star Robin Thicke will headline the festival tonight (September 24), while John Legend, Justin Timberlake and Tinie Tempah will perform in coming days, before Katy Perry closes the month-long event on September 30.