Planet NGTS-1b is a massive, 986-degrees-hot ball of gas revolving around a red M-dwarf star 600 light years from Earth.
It is the largest planet compared to the size of its star ever discovered.
But the discovery completely contradicts theories that a star so small could create such a huge planet.
The lead author of the research, Dr. Daniel Bayliss, of the University of Warwick’s Astronomy and Astrophysics Group, said: “The discovery of NGTS-1b was a complete surprise to us. Such massive planets were not thought to exist around such small stars.
“This is the first exoplanet we have found with our new NGTS facility, and we are already challenging the received wisdom of how planets form.”
Scientists previously thought small stars could form rocky planets but not gather enough material to form planets the size of Jupiter.
Red M-dwarf stars are the most common type in the universe and scientists believe there may be many more planets like this.
Warwick Professor Peter Wheatley said: “NGTS-1b was difficult to find, despite being a monster of a planet, because its parent star is small and faint.
“Small stars are actually the most common in the universe, so it is possible that there are many of these giant planets waiting to found.
“Having worked for almost a decade to develop the NGTS telescope array, it is thrilling to see it picking out new and unexpected types of planets.
“I’m looking forward to seeing what other kinds of exciting new planets we can turn up.”
The planet is about 2.8million miles away from its start which is only three per cent of the 93-million-mile distance between Earth and the Sun.
A year on NGTS-1b occurs every 2.6 Earth days.
The astronomer’s report called ‘NGTS-1b: a hot Jupiter transiting an M-dwarf’, will be published in the Monthly Notices of the Royal Astronomical Society.
The astonishing discovery comes as astronomers discovered 20 planets that have an atmosphere not too dissimilar to Earth and could support alien life.
Scientists made the discovery from the latest information from the powerful Kepler space telescope that reveals the worlds orbit stars similar to our own Sun.
Kepler team leader Jeff Coughlin said that one exoplanet was particularly exciting as it had an orbit of 395 Earth days and a similar size, while another just had an orbit of 18 days.
The Earth-like plant was about 97 per cent the size of Earth with a similar climate to our own tundra regions.
Although it had a chilly climate it was warm enough to hold liquid water, an essential element to support life.
Mr Coughlin told New Scientist: “If you had to choose one to send a spacecraft to, it’s not a bad option.”
He added: “If you had to choose one to send a spacecraft to, it’s not a bad option.”