The UK Health Security Agency (UKHCA) confirmed the positive case on Thursday following a set of tests.
It is believed the dog, which is recovering at home, contracted Covid from its owners, who had previously tested positive for the virus.
Experts say there is no evidence the animal was involved in the transmission of the disease to its owners, or that pets or other domestic animals are able to transmit the virus to people.
It is the first confirmed case of a dog becoming infected with coronavirus in the UK, after the virus was detected in a cat in the same laboratory last year.
The case has been reported to the World Organisation for Animal Health in line with international agreements.
Chief veterinary officer Christine Middlemiss said: “Tests conducted by the Animal and Plant Health Agency have confirmed that the virus responsible for Covid-19 has been detected in a pet dog in the UK.
“The infected dog was undergoing treatment for another unrelated condition and is now recovering.
“It is very rare for dogs to be infected and they will usually only show mild clinical signs and recover within a few days.
“There is no clear evidence to suggest that pets directly transmit the virus to humans. We will continue to monitor this situation closely and will update our guidance to pet owners should the situation change.”
Dr Katherine Russell, consultant medical epidemiologist at the UK Health Security Agency, said: “Covid-19 is predominantly spread from person to person but in some situations the virus can spread from people to animals.
“In line with general public health guidance, you should wash your hands regularly, including before and after contact with animals.”