Tony Eastlake, 55, known as the “flower man of Islington” by customers and his local community, died from a knife wound after being attacked on Essex Road just before 5.30pm on Saturday.
His family said he had worked on the Essex Road flower stall from the age of 14 and was “loved by everybody” in the community.
Police said on Tuesday that a 20-year-old man had been arrested on suspicion of his murder and that at this early stage, it is believed that the suspect was known to the victim.
Detective Chief Inspector Vicky Tunstall, leading the investigation, said: “Our dedicated team of officers have worked tirelessly since Saturday evening to identify the person suspected of the murder of Tony Eastlake.
“I hope this brings some reassurance to the community after what was an incredibly traumatic and unsettling incident that has cost the life of a well loved and respected man.
“I can confirm that this attack is not believed to have occurred as a result of a robbery.”
Officers are continuing to appeal for witnesses and have urged members of the public who live in or may have been driving through the area to check CCTV and dashcam footage for information.
Anyone with information is asked to call police on 101 quoting reference CAD 5562/29May, or to contact Crimestoppers on 0800 555 111.