The birth was announced Tuesday and pictures of the new cub were released, the Daily Mirror reported. But the new cub and its mother, Melati, will get several weeks of privacy, and keepers have not determined the cub's gender yet.
Melati, a 5-year-old endangered Sumatran tiger, is the offspring of Hari, the last tiger born at the zoo. The zoo did not announce her pregnancy, which lasted 105 days.
Paul Kybett, one of the keepers, described Melati as a "doting mom."
"We were nervous about the pregnancy, as it was Melati's first cub and we didn't know how she'd react," Kybett said. "When it came to her due date, we were all watching our monitors with bated breath.
The actual birth happened very quickly and Melati's maternal instincts kicked in immediately as she started licking the cub all over and it soon began wriggling around -- we couldn't have asked for a smoother birth."
The zoo in Regent's Park opened its new "tiger territory," designed to encourage captive breeding, six months ago.