At least 20 people died and over 100 were injured in the blast in Bangkok, including the British national who lived in Hong Kong.
“The loss of life and injury in Bangkok is horrific and I condemn this callous act of violence against completely innocent and unsuspecting members of the public,” Mr Hammond said in a statement.
“I can confirm that one British national, a resident of Hong Kong, lost her life in the attack. British Embassy staff in Thailand are assisting her family at this very difficult time.
“My thoughts are with the victims, their families and loved ones, and with the Thai people.
“Foreign Office officials are in close contact with the Thai authorities and have offered UK assistance in the investigation of this abhorrent act. “British nationals in Thailand should check the Foreign Office website for the latest travel advice.”
The reason for the attack is not yet known but Thai police have released CCTV footage of a suspect, who was seen with a backpack and then later without one, around the time of the blast.