The suspected suicide bomber threw himself at the convoy of the British envoy as it drove through the capital, Sanaa.
Ambassador Tim Torlot, 52, is safe, UK officials confirmed. One person – believed to be the attacker – was killed, Yemeni security sources said.
The attack bore all the "hallmarks of al-Qaeda", the Yemeni interior ministry said in a statement.
The UK Foreign Office has closed the embassy to the public.
Witnesses said the bomber was a young man who was wearing a school uniform, apparently as a disguise.
The attacker, believed to be wearing an explosives belt, was said to have thrown himself at the convoy, but was too slow to hit his intended targets.
There are mounting fears that Yemen is becoming a leading al-Qaeda haven.