Steven Dick, aged 37, was the Deputy Head of Mission for the British embassy in Budapest.
He passed away on Tuesday after contracting Covid-19, the Foreign Office said.
UK Foreign Secretary Dominic Raab said: “I am desperately saddened by the news of Steven’s death and my heart goes out to his parents Steven and Carol.”
“Steven was a dedicated diplomat and represented his country with great skill and passion. He will be missed by all those who knew him and worked with him.”
Dick joined the Foreign Office in 2008 and has also worked in British embassies in Riyadh and Kabul, according to his biography on the UK government’s website.
His role of Deputy Head of Mission made him a key adviser to the UK’s Ambassador to Hungary, Iain Lindsay. Dick has also worked in the UK government’s Department for Digital, Culture, Media and Sport.
“Steven was a much-loved son, grandson and nephew,” Dick’s parents said in a statement to the UK’s PA news agency.
“He was kind, funny and generous. It was always his dream to work for the Foreign & Commonwealth Office and he was very happy representing our country overseas.”
The UK has recorded more than 8,000 coronavirus cases and 435 deaths, while Hungary has 226 cases and 10 fatalities, according to Johns Hopkins University on March 25.