The Cardassian Occupation or simply the Occupation is a period in the fictional Star Trek universe affecting the planet Bajor and the Bajorans.

The period began in 2329 when the Cardassians landed on the planet to exploit its resources, brutally enslaving the inhabitants.

The Cardassians formally annexed the planet in 2339. All Bajorans were summoned to fight the Cardassian invaders regardless of their social status. As a result, the D'jarras, or Bajoran castes, were abolished.

The Occupation was the most brutal period in Bajoran history, the highly advanced Bajoran culture was damaged. Many people ended up in refugee camps where they were mistreated by the Cardassians. Bajor's natural resources were mined at notorious labor camps such as Gallitep which was commanded by the cruel Gul Darhe'el. Only their faith in the Prophets (embodied by Kai Opaka) made sure that the Bajoran people, and most important, the Bajoran culture survived.

As a result of the call to arms in 2339 many resistance cells were formed. The most notable resistance group was the Shakaar resistance cell, under the lead of Shakaar Edon, a local farmer from Dahkur province and future Prime Minister of Bajor.

Major Kira Nerys joined this resistance cell in 2355 and was involved in some terrorist attacks and she was apparently considered a threat to Cardassian troops as records of her resistance activities still exist on Cardassia.

In 2352 Gul Dukat became the last prefect of Bajor. He resided on the orbital mining station Terok Nor which was built a year earlier. The station greatly increased Cardassian mining operations and soon contained a sizable community of Bajoran forced laborers.

Not all Bajorans opposed the Cardassian occupation and a Bajoran occupational government existed consisting of Bajoran collaborators led by Kubus Oak. The Vedek Assembly was led likewise by Prylar Bek. Collaborators were often given better quarters to live in and food to eat than the average Bajoran. In 2365 a collaborator named Vaatrik was killed by Kira Nerys.

The Bajoran resistance launched their first off-world attack against the Cardassians at Pullock V.

In 2369 despite the objections of Gul Dukat the Cardassian civilian leaders led by Kotran Pa'Dar decided to withdraw Cardassian troops from Bajor leaving behind a devastated planet and the space station Terok Nor. Before leaving the Cardassian troops brought about as much destruction as they possibly could.

The effects of the Occupation are still visible, but Bajor is slowly recovering from the Occupation.