The crash happened in Willesden High Road at about 1pm on Saturday during a pre-planned operation to target the illegal use of e-scooters.
Officers had asked the man, 22, to stop riding his e-scooter, but he failed to do so. The e-scooter then collided with a police officer, knocking him to the floor.
The police officer was treated at the scene before being taken to hospital, where he has been treated for a broken leg and concussion.
The man was arrested at the scene on suspicion of section 18 grievous bodily harm, assault on an emergency worker, obstructing a drugs search, failure to stop, dangerous driving, driving without a license or insurance, breaching the terms of a prison sentence and being unlawfully at large.
Inspector Martin Robbie, of North West BCU, said: "Officers put themselves in the face of danger on a daily basis and an incident like this demonstrates this.
"I would like to remind the public that the use of e-scooters, unless subject to a government approved scheme, is prohibited and use upon public highways and spaces will be subject to enforcement and potential seizure of the e-scooter."
Earlier this month, a 16-year-old boy on an e-scooter was killed in a hit and run collision and a three-year-old girl left with life-changing injuries after being hit by a young man also riding an e-scooter.
E-scooters can be used on roads, in cycle lanes and on cycle paths, but are banned from being ridden on pavements.
Private e-scooters can only legally be used in the UK on private land but are a common sight on roads and pavements.
Last month, the Metropolitan Police said they had seized 507 private e-scooters over seven days.
Around 1,200 e-scooters are available to rent in the capital across nine boroughs.