The monarch met two victims of a recent stabbing attack when he made the unannounced visit to Golders Green, which is home to a sizeable Jewish population and has borne the brunt of the recent anti-Semitic incidents across the capital.
"Thank you, your majesty, for coming today to Golders Green to bring comfort and encouragement to our Jewish community!" UK Chief Rabbi Ephraim Mirvis, who was there to greet the King, said on X.
Last month, two Jewish men were stabbed in the area in an attack being treated by police as terrorism while in other incidents in Golders Green, four Jewish community ambulances were torched and a memorial wall targeted.
During his trip, Charles met the two stabbing victims at a Jewish Care charity centre as well as other religious and civic leaders.
The visit was Charles' latest demonstration of backing for the Jewish community, after he visited a synagogue in northern England following an attack last year that left two worshippers dead and agreeing in March to become the patron of a charity that provides security for the UK's estimated 290,000 Jews.
The recent attacks have led Mirvis to say the Jewish community was facing a sustained campaign of violence and intimidation.
The government has also raised its terrorism threat level to "severe" from "substantial" with Prime Minister Keir Starmer saying Jewish people were living in fear.
The King's visit comes on the same day that an article written by his younger son Prince Harry was published in which he said a rise in anti-Semitism in the UK was deeply troubling, and that any anger over events in the Middle East should not spill over into hatred.