Police stopped and searched 23 people at Stonebridge Park tube station yesterday as part of a crackdown on drug-related crime.
Tokyngton Safer Neighbourhoods Team worked with a dog unit to arrest four people.
The arrests were made for crimes including fraud, handling stolen goods, possession of blades and possession of cannabis.
One person was issued with a written charge at the scene for possession of cannabis and one cannabis warning was issued.
PC Rose Shepherd from Tokyngton Safer Neighbourhoods Team said: "This operation was conducted to reassure local residents who had complained about crime in the area.
“It was a successful day and shows we will not tolerate criminal activity in the area.
“This has had a positive impact on the local community and surrounding residential area in deterring criminal activity.”