Monothelitism, or monotheletism, is a theological doctrine in Christianity that was proposed in the 7th century, but was ultimately rejected by the sixth ecumenical council. It held Christ as having only one will and was thus contrary to dyothelitism, the Christological doctrine accepted by most Christian denominations, which holds Christ as having two wills (divine and human). Historically, monothelitism was closely related to monoenergism, a theological doctrine that holds Jesus Christ as having only one energy. Both doctrines were at the center of Christological disputes during the 7th century.

Monothelitism is from Greek: μονοθελητισμός, romanized: monothelētismós, lit. 'doctrine of one will'. Theological notions related to the oneness of Christ's will emerged as a result of some earlier Christological controversies that were related to monophysitism as formulated by Eutyches (d. 456) and miaphysitism as formulated by non-Chalcedonian followers of Cyril of Alexandria (d. 444). Since the notion of Christ's one nature implied the oneness of his will, ecclesiastical and political elites of the Eastern Roman Empire tried during the 7th century to promote monothelitism as a unifying doctrine that would reconcile divided Christian factions. In spite of strong imperial support, those attempts failed, and monothelitism was consequently rejected and denounced as heresy in 680–681 at the Third Council of Constantinople, the sixth ecumenical council.

Monothelitism is still today taught by some Protestant Christian philosophers, including William Lane Craig and J. P. Moreland. However, the dyothelite view is mainstream in all major branches of Christianity. Modern monothelitism is associated with a certain form of social trinitarianism.

During the 5th century, some regions of the Church were thrown into confusion because of the debates that erupted over the nature of Jesus Christ. Although the Church had already determined that Christ is the son of God, his exact nature remained open to debate. The Church had declared heretical the notion that Jesus is not fully divine in the 4th century (see First Council of Nicaea), during the debates over Arianism, and had declared that he is God the Son who became human. However, in arguing that he is both God and man, there then emerged a dispute over exactly how the human and divine natures of Christ actually exist within the person of Christ.

The Christological definition of Chalcedon, as accepted by the Eastern Orthodox, Catholic, Anglican, Lutheran, and Reformed churches, is that Christ remains in two distinct natures, yet these two natures come together within his one hypostasis. More simply, Christ is known as "both fully human and fully Divine, one in being with the Father". This position was opposed by the Monophysites who held that Christ possesses one nature only. The term Monophysitism of which Eutychianism is one type, held that the human and divine natures of Christ were fused into one new single (mono) nature. As described by Eutyches, his human nature was "dissolved like a drop of honey in the sea", and therefore his nature is really divine. This is distinct from Miaphysitism, which holds that, after the union, Christ is in one theanthropic (human-divine) nature and is generated from the union of two natures. The two are thus united without separation, without confusion, and without alteration, and with each having a particularity. Miaphysitism is the christological doctrine of the Oriental Orthodox churches.

Nevertheless, the resultant debates led the Chalcedonians to accuse the non-Chalcedonians of teaching Christ's humanity to be of a different kind from our own. Meanwhile, the non-Chalcedonians accused the Chalcedonians of espousing a form of Nestorianism, a doctrine rejected in the preceding council that held that Jesus Christ was two distinct subsistences.

This internal division was dangerous for the Byzantine Empire, which was under constant threat from external enemies, especially as many of the areas most likely to be lost to the empire (which did happen as a result of the wars with the Umayyad Caliphate) were the regions that were in favour of Monophysitism, and who considered the religious hierarchy at Constantinople to be heretics only interested in crushing their faith. In these provinces, the non-Chalcedonians were far more numerous than the Chalcedonians. In Egypt for instance, some 30,000 Greeks of Chalcedonian persuasion were ranged against some five million Coptic non-Chalcedonians. Meanwhile, Syria was divided between followers of the Chalcedonian Patriarch Paul I and Miaphysite Patriarch Sergius I, and Mesopotamia between Syriac Miaphysities and Nestorian Church of the East, while the church of Armenia was wholly Cyrilline Non-Chalcedonian, and Palestinian Patriarch fully adhered to Chalcedonianism. Consequently, the Monothelite teaching emerged as a compromise position. The Byzantine emperor Heraclius tried to unite all of the various factions within the empire with this new formula that was more inclusive and more elastic.

That approach was needed to win over the non-Chalcedonians since they already believed that Christ has a single nature and so necessarily believed that he holds a single will. However, it was unclear whether the Chalcedonians should believe in Christ's human and divine energy and/or will as well as his human and divine nature because the ecumenical councils had made no ruling on that subject. A ruling for the new doctrine would provide common ground for the non-Chalcedonians and the Chalcedonians to come together, as the non-Chalcedonians could agree that Jesus has two natures if he has only one will, and some Chalcedonians could agree that Jesus has one will if he has two natures.