Zoroastrian or Iranian cosmology refers to the origins (cosmogony) and structure (cosmography) of the cosmos in Zoroastrianism. Zoroastrian literature describing cosmographical beliefs include the Avesta (especially in its description of Avestan geography) and, in later Middle Persian literature, texts including the Bundahishn, Denkard, and the Wizidagiha-i Zadspram.

According to the Zoroastrian creation myth, there is one universal, transcendent, all-good, and uncreated supreme creator deity Ahura Mazda, or the "Wise Lord" (Ahura meaning "Lord" and Mazda meaning "Wisdom" in Avestan), omniscient although not omnipotent.

Ahura Mazda existed in light and goodness above, while Angra Mainyu (or "Ahriman") existed in darkness and ignorance below. They have existed independently of each other for all time, and manifest contrary substances. In the Gathas, Ahura Mazda works through emanations known as the Amesha Spenta and with the help of "other ahuras". These emanations support him and held to represent and guard different aspects of creation and the ideal personality. Ahura Mazda is immanent in humankind and interacts with creation through these bounteous/holy divinities. He is also assisted by a league of divinities called Yazatas, meaning "worthy of worship." Each is a hypostasis of a moral or physical aspect of creation. Asha is the main spiritual force which comes from Ahura Mazda. It is the cosmic order and is the antithesis of chaos, which is evident as druj, falsehood and disorder, that comes from Angra Mainyu. The resulting cosmic conflict involves all of creation, mental/spiritual and material, including humanity at its core, which has an active role to play in the conflict. The main representative of Asha in this conflict is Spenta Mainyu, the creative spirit/mentality. Ahura Mazda created the material and visible world itself in order to ensnare evil. He created the floating, egg-shaped universe in two parts: first the spiritual (menog) and 3,000 years later, the physical (getig). Ahura Mazda then created Gayomard, the archetypical perfect man, and Gavaevodata, the primordial bovine.

While Ahura Mazda created the universe and humankind, Angra Mainyu, whose very nature is to destroy, miscreated demons, evil daevas, and noxious creatures (khrafstar) such as snakes, ants, and flies. Angra Mainyu created an opposite, evil being for each good being, except for humans, which he found he could not match. Angra Mainyu invaded the universe through the base of the sky, inflicting Gayomard and the bull with suffering and death. However, the evil forces were trapped in the universe and could not retreat. The dying primordial man and bovine emitted seeds, which were protect by Mah, the Moon. From the bull's seed grew all beneficial plants and animals of the world and from the man's seed grew a plant whose leaves became the first human couple. Humans thus struggle in a two-fold universe of the material and spiritual trapped and in long combat with evil. The evils of this physical world are not products of an inherent weakness but are the fault of Angra Mainyu's assault on creation. This assault turned the perfectly flat, peaceful, and daily illuminated world into a mountainous, violent place that is half night. According to Zoroastrian cosmology, in articulating the Ahuna Vairya formula, Ahura Mazda made the ultimate triumph of good against Angra Mainyu evident. Ahura Mazda will ultimately prevail over the evil Angra Mainyu, at which point reality will undergo a cosmic renovation called Frashokereti and limited time will end. In the final renovation, all of creation—even the souls of the dead that were initially banished to or chose to descend into "darkness"—will be reunited with Ahura Mazda in the Kshatra Vairya (meaning "best dominion"), being resurrected to immortality.

Avestan sources regularly describe the cosmos as being constituted by the heaven and earth, for example, some phrases that appear include "we worship the earth and the heaven" and "between heaven and earth". The original separation of the heavens and the earth is attributed to Ahura Mazda. One text enumerates the elements of the cosmos as follows:

Seven referring to different kinds of stars;

Two referring to the Luminaries (Moon and Sun);

Three referring to the highest paradisiacal abode.