The star, 44 light years away has three planets, they said, and one of them is in the so-called Goldilocks Zone, the limited band of distance from a sun where temperatures are neither too hot nor too cold for liquid water to exist.
The team of German and British astronomers said the planet is likely receiving about the same amount of solar energy as Earth gets from our sun.
"The star HD 40307 is a perfectly quiet old dwarf star, so there is no reason why such a planet could not sustain an Earth-like climate," Guillem Angla-Escude of Germany's University of Goettingen told Sky News.
Of the more than 800 planets that have been discovered outside our solar system since the early 1990s, only a handful are in their star's habitable zone.
Fewer still are planets in the zone that rotate, as the one around HD 40307 does, to create a daytime and nighttime, which increases the chance of an Earth-like environment.
"Just as Goldilocks liked her porridge to be neither too hot nor too cold but just right, this planet, or indeed any moons that it has, lie in an orbit comparable to Earth, increasing the probability of it being habitable," astronomer Hugh Jones of the University of Hertfordshire in Britain said.
The finding was published in the journal Astronomy & Astrophysics.