The globe-trotting nature show, which spotlights the natural wonders in different continents each episode, was seen by nearly 7M people at 6.15PM on BBC One.
It was comfortably the most-watched show at the time, and its viewing share of 35.57% was ahead of the 27.17% the slot usually attracts, according to Barb ratings figures provided by overnights.tv.
Seven Worlds, One Planet beat the debut of Dynasties last year, which was seen by 5.7M, but could not compete with the premieres of Blue Planet II (10.4m) and Planet Earth II (9.2m) — although both these were shown at the later time of 8PM.
Seven Worlds, One Planet started in Antarctica and featured a dramatic scene in which a gentoo penguin tried to escape a pod of orcas — all filmed from the unique vantage of a drone. It also showed the effects of the climate emergency on grey-headed albatrosses in intimate scenes, while viewers also saw how humans butchered great whales to the point of extinction at the South Pole, but the population is now recovering.