Adjara has been part of Colchis and Caucasian Iberia since ancient times. Colonized by Greeks in the 5th century BC, the region fell under Rome in the 2nd century BC. It became part of the region of Egrisi before being incorporated into the unified Georgian Kingdom in the 9th century AD. The Ottomans conquerred the area in 1614. The people converted to Islam in this period. They were forced to cede Ajaria to the expanding Russian Empire in 1878.

After a temporary occupation by Turkish and British troops in 1918–1920, Ajaria was reunited with Georgia in 1920. After a brief military conflict in March 1921, Ankara government ceded the territory to Georgia due to Article VI of Treaty of Kars on grounds that autonomy is provided for the Muslim population. The Soviet Union established the Adzharian Autonomous Soviet Socialist Republic in 1921 in accord with this clause. Thus, Adjara was still a component part of Georgia, but with considerable local autonomy. Its Muslim population was repressed by Stalin.



After the dissolution of the Soviet Union in 1991, Ajaria became part of a newly independent but politically divided Republic of Georgia. It avoided being dragged into the chaos and civil war that afflicted the rest of the country between 1991–1993 due largely to the authoritarian rule of its leader Aslan Abashidze. Although he successfully maintained order in Adjara and made it one of the country's most prosperous regions, he was accused of involvement in organised crime – notably large-scale smuggling to fund his government and enrich himself personally – as well as human rights violations. The central government in Tbilisi had very little say in what went on in Adjara; during the presidency of Eduard Shevardnadze, it seemed convenient to turn a blind eye to events in Adjara.

This changed following the Rose Revolution of 2003 when Shevardnadze was deposed in favour of the reformist opposition leader Mikheil Saakashvili, who pledged to crack down on separatism within Georgia. In the spring of 2004, a major crisis in Ajaria erupted as the central government sought to reimpose its authority on the region. It threatened to develop into an armed confrontation. However, Saakashvili's ultimatums and mass protests against Abashidze's autocratic rule forced the Adjaran leader to resign in May 2004, following which he went into exile in Russia. After Abashidze's ouster, a new law was introduced to redefine the terms of Ajaria's autonomy – a measure which some have criticised as an effective elimination of most of the region's autonomous powers.

Russia maintains the 12th Military Base (the former 145th Motor Rifle Division) in Batumi. (Note: the promises made at the 1999 Istanbul OSCE conference were in regard to withdrawal of Russian forces from Vaziani, near Tbilisi, and Gudauta). This was a source of great tension with Georgia, which has threatened to block access to the facility. Following talks in March 2005, the Russian government proposed to begin the process of withdrawal later the same year. In late July, the Russian hardware began to leave the base in Batumi.

The status of the Ajarian Autonomous Republic is defined by Georgia's law on Ajaria and the region's new constitution, adopted following the ouster of Aslan Abashidze. The local legislative body, Supreme Council (parliament) of Adjara consists of 30 members and is elected for four years. The head of the region's government – the Council of Ministers of Adjara is nominated by the President of Georgia who also has powers to dissolve the assembly and government and to overrule local authorities on issues where the constitution of Georgia is contravened. Levan Varshalomidze is the current head of the Adjaran government.

Adjara is subdivided into six administrative units:

City of Batumi

District of Keda

District of Kobuleti

District of Khelvachauri

District of Shuakhevi

District of Khulo

Adjara is well-known for its humid climate (especially along the coastal regions) and prolonged rainy weather, although there is plentiful sunshine during the Spring and Summer months. Ajaria receives the highest amounts of precipitation both in Georgia and in the Caucasus. It is also one of the wettest temperate regions in the northern hemisphere. No region along Adjara's coast receives less than 2,200mm (86.6 inches) of precipitation per year. The west-facing (windward) slopes of the Meskheti Range receive upwards of 4,500mm (177 inches) of precipitation per year. The coastal lowlands receive most of the precipitation in the form of rain (due to the area's subtropical climate). September and October are usually the wettest months. Batumi's average monthly rainfall for the month of September is 410mm (16.14 inches). The interior parts of Adjara are considerably drier than the coastal mountains and lowlands. Winter usually brings significant snowfall to the higher regions of Ajaria, where snowfall often reaches several meters. Average summer temperatures are between 22-24 degrees Celsius in the lowland areas and 17-21 degrees Celsius in the highlands. The highest areas of Ajaria have lower temperatures. Average winter temperatures are between 4-6 degrees Celsius along the coast while the interior areas and mountains average around -3-2 degrees Celsius. Some of the highest mountains of Ajaria have average winter temperatures of -8-(-7) degrees Celsius.

According to the 2002 census, the population of Adjara is 376,016. The Adjarians (Ajars) are ethnographic group of Georgian people who speak a local dialect of the Georgian language. The written language is Georgian.

The Georgian population of Adjara had been generally known as "Muslim Georgians" until the 1926 Soviet census which listed them as "Ajars" and counted 71,000 of them. Later, they were simply classified under a broader category of Georgians as no official Soviet census asked about religion.

Ethnic minorities include Russians, Armenians, Greeks, Abkhaz, etc.