The victim was “found lying on the ground bleeding heavily” close to a Primark store on Kilburn High Road in Camden near to the junction with Brondesbury Villas, according to social media reports.
A post by Twitter account London 999 claims “one man has been rushed to hospital after being stabbed”.
It includes video of a large cordon and several police vehicles with flashing lights at the scene.
The road has been closed.
Metropolitan Police has been contacted for comment.
Knife crime remains a major problem in the UK, claiming the lives of many victims.
According to a Parliamentary report, in the year ending March 2020, there were around 46,000 (selected) offences involving a knife or sharp instrument in England and Wales.
London recorded the highest rate of 179 offences, involving a knife per 100,000 population in 2019/20.
This represents a slight increase on a rate of 169 in 2018/19.
In an effort to combat violent crime in London, the Mayor Sadiq Khan has funded a dedicated Violent Crime Taskforce of nearly 300 police officers focusing on the areas worst affected.
Mr Khan is providing £15 million annually to support its operation.
Additionally, the Met Police has introduced targeted patrols in the areas worst-affected by knife crime.