He championed Western military support early in the war and also often spoke on the telephone with Mr. Zelensky. Towards the end of his premiership, he was accused of using those calls to divert attention from escalating domestic scandals.
Since being ousted as Prime Minister in September, Mr Johnson has already earned more than £1 million in outside revenue from a number of business speeches around the world.
He has not visited Ukraine since leaving number 10, but last week he is said to be planning to visit President Zelensky, with whom he had a close friendship during his time in power.
Mr Johnson has spoken out on the conflict, calling on the West to increase its support for Ukraine, arguing that more military aid this year could end Putin’s “misadventure”.
He voiced his support at a panel in Davos for new laws to seize and sell sanctioned Russian assets, even though Rishi Sunak’s government has indicated that such legislation is unlikely to come.
Last week it emerged that Johnson had signed a deal with publisher HarperCollins to write a book about his two and a half years as prime minister, which has been called “a memoir like no other”.
He also plans to stand for re-election in his Uxbridge and South Ruislip constituency at the next general election.