In Sanskrit texts, Rāja yoga (/ˈrɑːdʒə ˈjoʊɡə/) was both the goal of yoga and a method to attain it. The term was later adopted as a modern label for the practice of yoga when Swami Vivekananda gave his interpretation of the Yoga Sutras of Patanjali in his 1896 book Raja Yoga. Since then, Rāja yoga has variously been called aṣṭāṅga yoga, royal yoga, royal union, sahaja marg, and classical yoga.

Rāja (Sanskrit: राज) means "king, sovereign, chief, best or most excellent of its kind". The historical use of the term Rāja yoga is found in other contexts, quite different from its modern usage. In ancient and medieval Sanskrit texts, it meant the highest state of yoga practice (one reaching samādhi).

The Hatha Yoga Pradipika (15th century) for example, authored by Swatmarama, presents Hatha Yoga as a preparatory and complementary practice that leads to the state of Raja Yoga:

Success in Raja Yoga cannot be attained without Hatha Yoga, nor can success in Hatha Yoga be attained without Raja Yoga. Therefore, both should be practiced until perfection is achieved. (2.76)

Raja Yoga is defined in the text as:

The union of the mind and the soul is called Raja Yoga. (4.77)

The author also warns against exclusive reliance on physical practices:

Those who are ignorant of Raja Yoga and practice only Hatha Yoga waste their energy fruitlessly. (4.79)