Basil II was born in 958, the son of the Emperor Romanos II and Empress Theophano. He was of the "Macedonian Dynasty" founded by his ancestor Basil I (867 to 886), although he may actually have been the descendant of Michael III (see Basil I). In 960, Basil, at the age of five, along with his brother Constantine (the future Constantine VIII) were associated by their father to the throne. Romanos died in 963. The two boys were too young to rule and their mother Theophano married one of Romanos' leading generals, who took the throne as the Emperor Nikephoros II Phokas. Nikephoros was murdered in 969 by his nephew John I Tzimisces, who then became emperor and reigned for seven years. When Tzimisces died on 10 January 976, Basil II finally took the throne as senior emperor, with Constantine as co-emperor.
In the early years of Basil's reign, the administration remained in the hands of the eunuch Basil Lekapenos (an illegitimate son of Emperor Romanos I). Basil was a brave soldier and a superb horseman, and he would prove himself as an able general and strong ruler. Constantine preferred a life of leisure and remained in the background. Two experienced generals, Bardas Skleros and Bardas Phokas had their eye on the throne. Both were eventually defeated (Skleros in 979 and Phokas in 989), by a ruthless Basil, with the help of 6000 Varangians supplied by Vladimir, Prince of Kiev. In return, Vladimir demanded to be married to Basil's younger sister Anna (963-1011). Basil hesitated, but when Vladimir promised to baptize himself and to convert his people to Christianity, Basil finally agreed. This marriage marked the beginning of the process by which the Grand Duchy of Moscow came into being.
Following the rebellions, Basil Lekapenos was accused of plotting with the rebels and exiled and his property confiscated. Basil also made war upon the system of huge estates in Asia Minor, which his predecessor, Romanos I, had endeavoured to check.
At the beginning of Basil's reign, there was a revolt in Bulgaria (which had been partly subjugated by John I Tzimiskes), leading to the rise of Samuel, the self-proclaimed Tsar of the Bulgars. There were many incursions into Byzantine territory after 980, and in 986 Samuel captured Larissa, chief city of Thessaly. Basil set forth with his army to attack Samuel, but they were ambushed at a pass known as Trajan's Gate and the army destroyed. Back in Constantinople, Basil made a solemn oath to take his revenge on the entire Bulgar nation.
By 991, with the defeat of his rivals, Basil was free to deal with the Bulgars and in spring of that year he set off for Thessalonica to start his campaign to recover lost territory. The tide turned in 996 when the Byzantine general Nikephoros Ouranos inflicted a crushing defeat on a Bulgarian army at a battle on the River Spercheios in Thessaly. Samuel and his son Gabriel were lucky to escape capture.
In 995 Basil was distracted by an appeal from the Emir of Aleppo who was being threatened by the Fatimid Caliph. The Aleppo and Antioch were under the protection of the Byzantines. In order to reach Aleppo quickly, Basil mounted his 40,000 strong army and reached Syria in 16 days, an unprecedented move and he was successful in raising the siege of Aleppo.
By 1000, he was free to focus on the conquest of Bulgaria itself. This was to be a long struggle but bit by bit territory was gained. In 1014 Basil was ready to launch a campaign to finally destroy Bulgarian resistance. On 29 July 1014, Basil II and his general Nikephoros Xiphias outmanoeuvred the Bulgarian army, which was defending one of the fortified passes, in the Battle of Kleidion. Samuel avoided capture only through the valour of his son Gabriel. Having crushed the Bulgarians, Basil exerted his vengeance by cruelty - he was said to have captured 15,000 prisoners and blinded 99 of every 100 men, leaving one one-eyed man in each cohort to lead the rest back to their ruler. Samuel died two days later, on 6 October 1014, after suffering a stroke. Although the mistreatment of the Bulgarian prisoners may have been exaggerated, this incident helped give rise to Basil's Greek epithet of Boulgaroktonos, meaning "the Bulgar-slayer", in later tradition. Bulgaria fought on for four more years but it finally submitted in 1018.
The neighbouring rulers of Croatia, Krešimir III and Gojslav, who were previously allies of Bulgaria, accepted Basil's supremacy in order to avoid the same fate as Bulgaria. Basil showed considerable statesmanship in his treatment of the defeated Bulgarians, giving many former Bulgarian leaders court titles, positions in provincial administration, and high commands in the army.
In 1016, Byzantine armies attacked the Crimea, much of which had fallen under the sway of the Khazar successor kingdom of George Tzoul, based at Kerch. Subsequently the Byzantines occupied the southern Crimea.
Gains were also made in Armenia and in the meantime, other Byzantine forces restored much of Southern Italy, lost over the previous 150 years.
Basil was preparing a military expedition to recover the island of Sicily when he died, on 15th December 1025. He was succeeded by his brother Constantine VIII who proved to be an ineffectual ruler.