The Planetary Union is a federation of space flight-capable species, based at Planetary Union Central on Earth. The Union consists of science and exploratory vessels, a unified military, and a quasi-government overseeing affairs among colonies. According to Admiral Halsey and Captain Ed Mercer, the combined Union fleet of the year 2419 is roughly 3,000 vessels. The Union's history is almost completely obscure, including details of its foundation and development.
- Earth (Humans)
- Moclus (Moclans)
- Xelaya (Xelayans)
- Unnamed Planet (Retepsians)
- Unnamed planet (Jelly)
- Kaylon 1 (Kaylons): Though not a member world and despite their sense of superiority to humanoid life, Kaylon is on friendly terms with the Union to the point that they have assigned a representative to serve on a Union vessel in order to study human behavior.
- Calivon: The Calivon are technologically more advanced and regard Union planets as inferior life forms. While the Calivon are not hostile towards the Union, they are dangerous, and the Union strictly forbids any avoidable contact with them.
- Krill: Krill follow the Anhkana, a religious text that teaches that they are superior to all other life. Krill warships have attacked several Union colonies and vessels. There is no declared state of war between the Union and Krill, chiefly because a protracted conflict would jeopardize the stability of the Union.
- Lopovius (Navarians, Bruidians): Both species of Lopovius are neighbors and allies of the Union, but were engaged in a long dispute focused on a planet at the Union border. Neither species is original to Lopovius, but originate from another unnamed planet or planets. In the episode Cupid's Dagger, both species agree that the Union would serve as a neutral host in the interest of peace talks.
Within the Planetary Union fleet, there are six Divisions, or Crew Ranks:
The admirals use a golden insignia of the Planetary Union with a purple uniform.
The commanders and executives use a silver insignia of the Planetary Union with a blue uniform.
Commanders are the heads of Union ships. Executives include the first officer and second officer under the ship's captain.
The scientists use an insignia of an atom-like emblem with a green uniform. Scientists specializing in medical care however use an insignia of a green cross surrounding an atom.
The engineers use an insignia of engine gears with an orange uniform.
The security personnel use an insignia of wings over a shield with a red uniform.
Ensigns are the juniormost officers within the Union. Their rank is bestowed upon graduation from Union Point and after assignment within the Union. Lieutenants and Lieutenant Commanders oversee departments on a ship such as security or engineering. Commanders serve as first officer to a captain, while the captain is the highest authority of a ship. Flag officers oversee the operation of fleets of ships or issue portfolios from Union Central.
Eight Planetary Union spaceships are known to exist, and most are named after aviation and space pioneers from Earth.
- USS Blériot A non-military, civilian transporter named after Louis Blériot. This ship was a holographic recreation used as a lure by the Calivon. 
- USS Chanute. Mentioned by Commander Kelly Grayson as the ship of a particularly talented young lieutenant commander. Named after Octave Chanute.
- USS Clemens
- USS Druyan. A non-military, colony transport named after Ann Druyan.
- USS Olympia (LCV-529) A Leviathan-class heavy cruiser and flagship of Admiral Ozawa.
- USS Olympia(SCV-183) A non-military, scientific cruiser. In Cupid's Dagger, the Olympia hosts Darulio while he waits to rendezvous with the Orville.
- USS Orville (ECV-197) A mid-level exploratory vessel, under the command of Captain Ed Mercer. The ship is named for Orville Wright. It is the title ship of the show.
- The Planetary Union is often compared to the United Federation of Planets in the Star Trek franchise.
- Lopovius is the only known Union planet revealed to be the home of two different recognized species.
- According to Joseph Porro the lowest rank in the Union wear Grey uniforms. What exactly position that entails is currently unrevealed.