Unification or unification theory may refer to:

• Unification (computer science), the act of identifying two terms with a suitable substitution
• Unification (graph theory), the computation of the most general graph that subsumes one or more argument graphs (if such a graph exists)
• Han unification, an orthographic issue dealt with by Unicode

• Unification (physics) of the observable fundamental phenomena of nature is one of the primary goals of physics
• Grand Unified Theory, a model in particle physics
• Unified field theory, a type of field theory

• Unification (album), a 1998 album by the band Iron Savior
• "Unification" (Star Trek: The Next Generation), a two-part episode of Star Trek: The Next Generation

• The act of producing an undisputed championship in boxing
• The act of producing an undisputed championship in professional wrestling

• Semantic unification, in philosophy, linguistics, and computer science
• Unification Church or Movement, a spiritual movement founded in Korea
• Unification or re-unification of sovereign states, see political union

• Unification Church
• Unionism (disambiguation)
• Unified (disambiguation)