Police were called to the crash on the junction of Barking Road and High Street South around 9.10pm today (March 12).
Officers, the air ambulance and paramedics attended the scene outside Newham Town Hall.
A man in his 30s was taken to hospital with injuries thought to be life-threatening.
There have been no arrests and while enquiries continue road closures are in place from Barking Road to Leyton Way, and on High Street South.
A Metropolitan Police spokesperson said: “Police were called to Barking Road, E6 at around 09:10hrs on Wednesday, 12 March to reports of a collision between a lorry and a pedestrian.
“Officers attended alongside the London Ambulance Service and London’s Air Ambulance.
“One man in his 30s, the pedestrian, was taken to hospital for treatment.
“His injuries are believed to be life-threatening. There have been no arrests.
“Enquiries are ongoing. Road closures remain in place from Barking Road to Leyton Way. High Street South is also closed.
“Anyone with any information, including dash cam footage, should contact 101 quoting reference 1701/12MAR.”
A London Ambulance Service spokesperson said: “We were called at 9.06am today (12 March) to reports of a road traffic collision at the junction of Barking Road and High Street North, East Ham.
“We sent resources to the scene, including an ambulance crew, a paramedic in a fast response car, an incident response officer and a trauma team in a car from London’s Air Ambulance.
“Our first paramedics arrived on scene in two minutes.
“We treated a man and took him to a major trauma centre.”
