The concert 'turns the flash mob on its head', according to an O2 statement. Rival T-Mobile, part of the Everything Everywhere group, regularly uses flash mobs for its ad campaigns.
O2's concept instead uses the 'flash exit' to empty public spaces to leave just a single fan standing.
In this case, the fan is unsuspecting 21-year-old Katie Hobbs from Southampton, chosen through a competition run via Facebook.
During the concert, the other 'fans' retreat to leave Katie alone with Tinie Tempah, who directs the remainder of the concert at her.
The 60-second ad, filmed by documentary maker Phil Griffin, will screen in two spots - on Saturday during 'Britain's Got Talent' and Channel 4's 'Million Pound Drop Live'.
O2 created the ad with experiential agency Pd3, and launched a website, www.thinkingofkatie.co.uk, which will also show a behind-the-scenes documentary to support the campaign. The 'Always thinking of you' campaign launched in February.Shadi Halliwell, head of brand at O2, said: "We're always thinking of our customers and go to extraordinary lengths to try and illustrate how valued they are in our eyes.
"In Katie's case, that meant arranging the smallest ever gig by the UK's hottest music star. She really did receive a unique experience and judging by her reaction, it seems to have worked."
Media was by ZenithOptimedia.