The bomb, thought to weigh around 500lb, was unearthed at a building site near the junction of Temple Street with Old Bethnal Green Road.
Residents living within a 100m hazard zone have been told to stay away for 24 hours while specialists investigate the device.
The Ministry of Defence said bomb disposal experts were at the scene.
A council spokesman told residents and visitors to "avoid the area".
"We have set up a rest centre in a local school with a full team en route to the school," he added.
The Ministry of Defence said military personnel from the Royal Logistics Corps were expected to "work through the night to stabilise and defuse the bomb".
An Army spokesperson said: "As with previous incidents, it is important that people follow any advice given by the police.
"The military Explosive Ordnance Disposal teams have extensive experience with these situations, having operated in Iraq, Afghanistan and Northern Ireland."
Earlier this year they detonated similar devices discovered in Wembley and Bermondsey.
Rachel Walker tweeted: "Total evacuation now. Not allowed back in the flat. Minimum 24 hour evacuation."
An unexploded World War Two bomb has been found in Bethnal Green, prompting an evacuation of 130 people.