Shops in Clapham, Peckham, Woolwich, Lewisham, Enfield, Walthamstow and Tottenham, among other places, were ransacked as rioting continued for the third consecutive day on Monday.
Youths caught up in the thrill of criminality filled their arms with loot and fled into the night, the Daily Mail, reported.
In many areas, looters parked their cars in side streets, masked up into shopping areas and robbed as much as they could carry, the Mail said.
On Tuesday morning, Scotland Yard said more than 300 people had been arrested, 69 people charged and two cautioned in connection with the rioting and looting across the city.
Commander Christine Jones said events were "simply inexcusable".
"Ordinary people have had their lives turned upside down by this mindless thuggery," she said.
Rioters took to the streets of Birmingham, Bristol and Liverpool throughout Monday night in copycat attacks. Cars were set alight in Liverpool, and police officers were pelted with makeshift weapons, including golf clubs as they tried to contain the gangs.
Police say sites such as Twitter, as well as BlackBerry handsets, were used to co-ordinate attacks on police and tell potential rioters where to find violence hotspots.
Shops selling luxury goods were the obvious targets of the looters. Police said the majority of opportunistic thieves were young, aged in their teens and early twenties.
Mobile phone and jewellery shops were damaged and plundered amid the violence, and at least one Twitter image showed a young man wheeling a trolley full of looted goods.
Looting quickly spread in Tottenham, with high-street giants Currys, Argos, Comet and PC World the most popular among thieves.
The Barclays Bank branch in Tottenham High Road was targeted, with rioters smashing their way into the branch and its cashpoint machine ripped from the wall and emptied.
But Twitter was also being used to warn people away from the area, with many tweets telling peaceful residents of the affected areas to keep away from flashpoints.
Metropolitan Police Commander Hanstock said: "Our priority will always be to try to preserve life, and with the numbers of people on the street and violence being directed at the police and fire service this had to remain our priority.
"We are aware that a number of shops were looted and this is very regrettable."