Kepler-33 is a star with 1.29 times the mass of the Sun, and 1.82 times its radius. It is located 3943.75 light years away from the solar system and is estimated to be 4.27 billion years old, as compared to the Sun which is roughly 4.6 billion years old.

Kepler-33 is known to have 5 exoplanets in orbit around it.

Kepler-33 b was discovered by the Kepler observatory, in 2012-05, using the transit method. Its semi-major axis is 0.07 astronomical units, as compared to Earth's which is 1 astronomical unit. The mass of Kepler-33 b is 3.689 times the mass of Earth. The radius of Kepler-33 b is 1.740 that of Earth. At 3.689 Earth masses, Kepler-33 b is a so called Super Earth. Super Earths could be terrestrial worlds like Earth, but they could also be ocean worlds or terrestrial worlds wrapped in a substantial atmosphere, in which case some refer to them as Mini Neptunes. No Super Earths are known to exist in our solar system, but if it exists, the so-called Planet Nine could very well be a super Earth, as it is hypothesized to have a mass between five and ten Earth masses.

Kepler-33 c was discovered by the Kepler observatory, in 2012-05, using the transit method. Its semi-major axis is 0.12 astronomical units, as compared to Earth's which is 1 astronomical unit. The mass of Kepler-33 c is 0.391 times the mass of Earth. The radius of Kepler-33 c is 3.200 that of Earth. With a mass below 5 Earth masses, a density of 0.13, and a semi-major axis of 0.1189 astronomical units, Kepler-33 c could, potentially, be an ocean world - a planet with no dry land.

Kepler-33 d was discovered by the Kepler observatory, in 2012-05, using the transit method. Its semi-major axis is 0.17 astronomical units, as compared to Earth's which is 1 astronomical unit. The mass of Kepler-33 d is 3.911 times the mass of Earth. The radius of Kepler-33 d is 5.350 that of Earth. With a mass below 5 Earth masses, a density of 0.25, and a semi-major axis of 0.1662 astronomical units, Kepler-33 d could, potentially, be an ocean world - a planet with no dry land.

Kepler-33 e was discovered by the Kepler observatory, in 2012-05, using the transit method. Its semi-major axis is 0.21 astronomical units, as compared to Earth's which is 1 astronomical unit. The mass of Kepler-33 e is 5.575 times the mass of Earth. The radius of Kepler-33 e is 4.020 that of Earth. At more than 10 Earth masses, Kepler-33 e is an ice giant, a planet that is made up mostly of volatiles like water, amonia and methane, and enveloped by a dense hydrogen and helium atmosphere, much like Uranus and Neptune in our solar system.

Kepler-33 f was discovered by the Kepler observatory, in 2012-05, using the transit method. Its semi-major axis is 0.25 astronomical units, as compared to Earth's which is 1 astronomical unit. The mass of Kepler-33 f is 9.604 times the mass of Earth. The radius of Kepler-33 f is 4.460 that of Earth. At more than 10 Earth masses, Kepler-33 f is an ice giant, a planet that is made up mostly of volatiles like water, amonia and methane, and enveloped by a dense hydrogen and helium atmosphere, much like Uranus and Neptune in our solar system.