Eight venues in the hip Shoreditch neighbourhood hosted 50 concerts by indie, electro and rock acts in a prelude to the main festival, which takes place in Reykjavik on October 15-19.
Weekend gig-goers packed the streets as they moved between shows by Young Knives, Digitalism, The Teenagers, and Florence and the Machine.
The first Iceland Airwaves festival took place in a Reykjavik aircraft hanger in 1999 and showcased up-and-coming Icelandic talent alongside established international acts such as Fatboy Slim and Chk Chk Chk.
"It is really a local festival," said Michael Szpiner, bass player with French group The Teenagers.
"All the people live nearby, the musicians as well as the festival-goers, along with the fashionistas and the Hoxtonites."
A Hoxtonite tends to refer to anyone who frequents the bars and clubs around Hoxton Square, a popular meeting place in the heart of Shoreditch.
"It is a festival which is meant to appeal to the young and trendy," added Fabien Mazzola, a local concert-goer.
"London is the inevitable choice if you want to forge an international reputation to match that of the Sziget and the Sonar festivals," he said, referring to festivals in Hungary and Spain.
"East London is the obvious place to be if you want good exposure to a young audience who are already saturated with musical and artistic offerings."
The British capital hosts around 20 mini-festivals annually that compete against larger provincial events such as Bestival on the Isle of Wight and Glastonbury, the biggest of them all, in southwestern Somerset.
"It is a small festival, in the best sense of the term," Henry Dartnall, lead singer of the Young Knives told AFP on Saturday.
"When you're playing guitar, you're free to improvise, let yourself go and then you go and listen to something else and mingle with the crowd."
In the courtyard of 93 Feet East, a Brick Lane venue that hosted five concerts in collaboration with French label Kitsune, artists and festival-goers all mingled freely in a mass of eccentric haircuts and outlandish apparel.
"It's a good way of getting known," said British singer James Yuill, acknowledging the value of being on the same bill as German electro duo Digitalism and up-and-coming Brit act Florence and the Machine.