The Mantrika Upanishad (Sanskrit: मन्त्रिक उपनिषत्, IAST:Māntrika Upaniṣad) is a minor Upanishad of Hinduism. The Sanskrit text is one of the 22 Samanya Upanishads, is part of the Vedanta and Yoga schools of Hindu philosophy literature, and is one of 19 Upanishads attached to the Shukla Yajurveda. In the Muktika canon, narrated by Rama to Hanuman, it is listed at number 32 in the anthology of 108 Upanishads.

The Upanishad comprises 21 verses. It attempts a syncretic but unsystematic formulation of ideas from Samkhya, Yoga, Vedanta and Bhakti. It is therefore treated as a theistic Yoga text. Mantrika suggests the theory, according to Paul Deussen's interpretation, that the universe was created by Purusha and Prakriti together, and various active soul-infants drink from inactive Ishvara soul (God) who treats this as a form of Vedic sacrifice. Dalal interprets the text as giving an exposition on Brahman (changeless reality) and Maya (changing reality, metaphysical illusion). According to the Mantrika Upanishad, "the Brahman dwells in body as soul, and this soul as God changes dwelling thousands of time".

The Mantrika Upanishad is also called Culika Upanishad (Sanskrit: चूलिका उपनिषत्).

Mantrika means "enchanter, reciter of spells", while 'Cūlikā' means "tip, summit, top of a column". The basis for the title of the Upanishad is unclear, but may refer to the phrases in the text on "pointed top of a pillar" and its extensive use of mantra metaphors and riddle-like terms from Atharvaveda known partly for its esoteric teachings of spells and enchantment.

Different schools of Hindu philosophy have varied in their classification of Mantrika Upanishad. The 11th-century scholar Ramanuja, of Vishishtadvaita school, for example, quoted from Mantrika Upanishad, but classified Mantrika as an Atharvaveda Upanishad. The anthology in the Muktika Upanishad, however, lists it as attached to the White (Shukla) Yajurveda.

The Mantrika Upanishad (or Culika Upanishad), suggested Mircea Eliade, was "probably written at the same period as the Maitri Upanishad, and in it we find the simplest form of theistic Yoga". It is one of the earliest theistic yoga texts. The relative chronology of the text is likely to have been in the final centuries of 1st millennium BCE, contemporaneous with the didactic parts of the Mahabharata, and probably earlier than the Vedanta-sutras and the Yoga-sutras. The Upanishad attempts a synthesis of Samkhya, Yoga, Vedanta and Bhakti devotionalism ideas, but with a hazy syncretism and poor organization, suggesting that the text may be from a period where these ideas were being formulated.

The text has a poetic structure and has 21 verses. For example, verses 17–18 of the text state,

In him in whom this universe is interwoven,
Whatever moves or is motionless,
In Brahman everything is lost,
Like bubbles in the ocean.

In him in whom the living creatures of the universe,
Emptying themselves become invisible,
They disappear and come to light again,
As bubbles rise to the surface.