That's according to Sky News, Ukrinform reports.
The appeal aims to help hospitals that are treating the sick and injured and run the risk of running out of vital items within weeks if they do not receive donations.
On Friday, the former prime minister visited a warehouse in Enfield, north London, where supplies from independent hospital provider Circle Health have been gathered.
He was accompanied by Ukrainian Ambassador Vadym Prystaiko to see first-hand the logistics of transporting hospital kit in bulk across Europe via lorry.
Following the visit, Johnson called upon the Great British public and their "generosity of spirit" asking them to donate to the appeal.
He said: "Not one bandage or bed you fund will go to waste in the Herculean task of rebuilding beautiful, brave Ukraine."
According to the report, a team of Ukrainian doctors working for Circle Health in the UK liaise directly with medics and inform the company about hospital equipment shortages in real time. Items are then gathered from Circle Health's 53 hospitals across every region of the UK, and sorted and loaded at their Enfield warehouse. Dedicated employees then volunteer to drive the loads across Europe into the heart of war-torn areas of Ukraine.
Circle Health has delivered nearly 300 tonnes/£3m worth of medical supplies in 13 lorry loads to hospitals across Kyiv, Kharkiv, Mykolaiv, Odesa, Lviv and Kherson. Delivered items to date include hundreds of wheelchairs, crutches, scrubs, bandages, ambulances, operating tables, hospital beds, ventilators, anesthetic machines and prosthetics.