Ukrainian President Volodymyr Zelensky has said Boris Johnson is a “big friend” of his country and should not “disappear” after he stands down.
Speaking to TalkTV, he said he would like the UK prime minister to remain “somewhere in politics in a position to be someone”.
Mr Johnson presented Mr Zelensky with the Sir Winston Churchill Leadership Award on Tuesday.
The prime minister is due to leave office on 6 September.
This will follow the announcement the previous day of his successor – either Foreign Secretary Liz Truss or former chancellor Rishi Sunak – after Conservative Party members have voted for a new leader.
The UK is one of the leading donors of military and humanitarian aid to Ukraine, and has imposed sanctions on Russian targets.
Mr Johnson has visited Ukraine several times since Vladimir Putin launched the invasion on 24 February.
The Sir Winston Churchill Leadership Award, which the prime minister presented to Mr Zelensky in a Downing Street ceremony via a video link, recognises “extraordinary leadership by individuals”.
Previous recipients include the Prince of Wales, UK prime ministers Sir John Major and Baroness Thatcher, and US secretaries of state Madeleine Albright and James Baker.
Speaking alongside his wife, First Lady Olena Zelenska, to Talk TV’s Piers Morgan Uncensored, Mr Zelensky said: “I have no right to play in politics inside the UK. What I can say is [Mr Johnson] is a big friend of Ukraine.
“I want him to be somewhere in politics in a position to be someone. I don’t want him to disappear, but the decision is in the hands of the British people.
“But I am sure that whatever position he is going to take, he is always going to be with Ukraine. This is from the heart.”
Asked about what he would say to Ms Truss or Mr Sunak, he replied that he would be “happy to cooperate” with either as prime minister, “like we used to have with Boris”.
“I know those two candidates are very respectful, and they have the support of the people and the society from the UK,” Mr Zelensky said.
“We know about this support. We know about the positive strength of those leaders.”
Mr Johnson announced his resignation as prime minister on 7 July, less than three years after gaining a landslide victory at the 2019 general election.
Months of criticism over parties in Downing Street during Covid lockdowns and other controversies prompted widespread calls for him to go, including among his own MPs.