Monday’s attack occurred in Leicester Square, a magnet for tourists with its shops, theatres and cinemas.
The square and surrounding area have an estimated 2.5 million visitors every week.
Police said the two victims were taken to a major trauma centre. The extent of their injuries was not immediately clear.
It was not immediately clear whether the stabbing had any link to the unrest.
Police had been braced for further riots over the weekend, but no widespread unrest emerged.
Ministers remained on high alert, Prime Minister Keir Starmer’s office said, adding its work was not done in dealing with the fallout from the violence.
