Neo-Ba'athism is a far-left variant of Ba'athism that became the state ideology of Ba'athist Syria, after the Arab Socialist Ba'ath party's Sixth National Congress in October 1963. As a result of the 1966 Syrian coup d'état launched by the neo-Ba'athist military committee led by Salah Jadid and Hafez al-Assad, Ba'ath party's Syrian regional branch was transformed into a militarist organization that became completely independent of the National Command of the original Ba'ath Party.

Neo-Ba'athism has been described as a divergence from Ba'athism proper that had gone beyond its pan-Arabist ideological basis by stressing the precedent of the military and purging the classical Ba'athist leadership of the old guard, including Michel Aflaq and Salah al-Din al-Bitar. The far-left neo-Ba'athist regime in Syria, which was influenced by various Marxist ideological schools, espoused radical leftist doctrines such as revolutionary socialism abandoned pan-Arabism, sought to strengthen ties with the Soviet Union, and came into conflict with Arab nationalists such as Nasserists and the Iraqi Ba'athists, particularly Saddamists, with whom they maintained a bitter rivalry. From their seizure of power in the Syrian Arab Republic as a result of the 1963 Syrian coup d'état, neo-Ba'athist officers purged traditional civilian elites to establish a military dictatorship operating along totalitarian lines.

Neo-Ba'athism is primarily associated with Assadism, based on the policies of the successive governments of Hafez al-Assad and his son Bashar al-Assad. This system was largely characterized by nepotism and sectarianism, with Hafez al-Assad's seizure of power in the 1970 Syrian coup d'état leading to the consolidation of Alawite minority dominance within the military and security forces. State propaganda portrayed Assadism as a neo-Ba'athist current that evolved Ba'athist ideology with the needs of the modern era. Neo-Ba'athism has been criticized by the founder of Ba'athist ideology, Michel Aflaq, for diverging from the original principles of Ba'athism.

A series of revolutionary offensives launched by the Military Operations Command and allied militias in late 2024 led to the collapse of the Assad regime in December 2024. Since then, remnants of the Ba'athist military apparatus and Assad family loyalists have engaged in violent clashes across Alawite strongholds in Latakia, Tartus and parts of Western Syria.

The pro-Marxist resolutions and declarations, such as the espousal of "class struggle" and "scientific socialism", adopted by the Ba'ath party during its 6th national congress set the ideological foundation of neo-Ba'athism. The main ideological document that became the basis of neo-Ba'athism and was adopted at the Sixth Congress was the so-called Muntalaqat. Between 1963 and 1966, neo-Ba'athists exercised the de-facto political power in Ba'athist Syria and were able to steer their ideological goals through the 1963 provisional Ba'athist constitution and its 1964 amendment. They also carried out purges within the Syrian Arab Armed Forces, as part of their efforts to subordinate the civilian old guard of the National Command of the Ba'ath Party and create an "ideological army" that was loyal to neo-Ba'athist officers. In foreign policy, neo-Ba'athists favoured the Socialist Bloc and were proponents of establishing a close alliance with the Soviet Union. The Maoist military concept of "people's war of liberation" played a central role in neo-Ba'athist ideology, and this was reflected in Ba'athist Syria's endorsement of socialist and left-wing Palestinian fedayeen groups in their guerrilla war against Israelis. In the economic sphere, neo-Ba'athists favoured the establishment of a socialist command economic system; and advocated the nationalization of private industries and radical land confiscation policies.

Neo-Ba'athism advocated the creation of a "vanguard" of leftist revolutionaries committed to build an egalitarian, socialist state in Syria and other Arab countries before making steps to achieve pan-Arab unity. The vanguard organisation in neo-Ba'athist ideology was the Arab Socialist Ba'ath party; which advocated class-struggle against the traditional Syrian economic elite classes; the big agriculturalists, industrialists, bourgeoisie and feudal landlords. By the 1970s, 85% of agricultural lands were distributed to landless peasant populations and tenant farmers. Banks, oil companies, power production and 90% of large-scale industries were nationalised. The neo-Ba'athists faction led by Salah Jadid concentrated on organizing the Syrian economy along socialist lines and exporting the doctrines of class-conflict and militant socialist revolution to the neighbouring countries. This view was challenged by General Hafez al-Assad and his neo-Ba'ath faction; who were proponents of a military-centric approach and focused on a strategy of strengthening the Syrian military to defend the socialist government against imperialist forces and their alleged internal collaborators. Assad favoured reconciliation of various leftist factions and pursued better relations with other Arab states. Although majority of the party members favoured Salah, Hafez was able to gain the upperhand following the events of the 1970 coup dubbed the "Corrective Revolution" in official Syrian Ba'ath history. Assad's victory also marked the supersedure of the military over the Ba'ath party structures; making the armed forces a central centre of political power.

The 6th National Congress of the Ba'ath party declared the party's ideological end-goal to be the socialist transformation of society through a Leninist strategy. Some Theoretical Propositions, a core ideological document adopted by the congress stated: "Socialism is the true goal of Arab unity. ... Arab unity is the obligatory basis for constructing a socialist society." Thus, neo-Ba'athists viewed pan-Arabism as a means to achieve their radical socialist objectives.

Neo-Ba'athism views religion as the "foremost symbol of reaction" preventing the birth of a modern socialist society, and advocate strict state supervision over religious activities for sustaining what its ideologues regard as a healthy, secularist society. During Salah Jadid's reign in power, the Ba'ath postured itself as a strongly anti-religious political entity; adhering to the Marxist–Leninist approach of top-down regimentation of the society through liquidation of what it regarded as "reactionary" classes such as the traditional ulema. The Grand Mufti's official status was downgraded by the Ba'athist government and the conventional role of religious clergy in state functioning was curtailed. While state ministers, officials, educators, etc. regularly preached about the "perils of religion"; party periodicals and magazines during the 1960s regularly made predictions about the "impending demise" of religion through the socialist revolution.