According to the Sky News broadcast from the scene, Johnson laid a wreath at the entrance to a Methodist church in Essex, where the parliamentarian was attacked.
In addition to the British Prime Minister, British Interior Minister Priti Patel and opposition leader Kir Starmer also visited the scene.
British MP David Amesse was stabbed several times while meeting with voters at a church on 15 October.
The police promptly detained the attacker.
Law enforcers called the murder of a member of parliament a terrorist act.
The British Parliament lowered flags in connection with the incident.