Vikramaditya ascended the Chalukya throne by deposing his elder brother Somesvara II, with the help of some of the Chalukya feudatories and by utilising the opportunities arising out of a conflict with the Cholas.
As soon as Somesvara II, the eldest son of Somesvara I came to the throne, Vikramaditya started planning his overthrow. Making use of the Chola invasion, he, along with some of the feudatories of Somesvara, especially the Seuna, the Hoysalas and the Kadambas of Hangala achieved his goal. Vikramaditya went into negotiations with the Chola king Virarajendra Chola. Vikramaditya consented to rule the Vengi kingdom as the Chola feudatory. Virarajendra also forced Somesvara to bifurcate his kingdom and let Vikramaditya rule the southern half (Gangavadi) independently.
Vikramaditya married one of Virarajendra's daughters to strengthen the alliance with the Cholas.
During this time Virarajendra Chola died (1070) and his son Athirajendra Chola came to the throne. Vikramaditya soon found his Chola alliance a liability. Rajendra Chalukya (future Kulothunga Chola I), a Vengi prince with close Chola connection, having been denied his rightful place on the Vengi throne by Vikramaditya, wanted to assume the Chola throne instead. Rajendra Chalukya had his opportunity when civil disturbances arose in the Chola kingdom. To quell rioting in Kanchipuram Vikramaditya led his forces into the city to assist his brother-in-law Athirajendra. Vikramaditya soon after proceeded to the Chola capital and helped Athirajendra inaugurate his reign and to defeat any attempts by Rajendra Chalukya to overthrow the rightful Chola king.
Satisfied that order had been restored, Vikramaditya returned to his capital. But news soon came to him that Athirajendra had been murdered in the civil uprising and Rajendra Chalukya had assumed the Chola throne under the title Kulothunga Chola I.
Vikramaditya now found enemies on both sides of his domain: Kulothunga in the south and his brother in the north. Vikramaditya spent the next six years to protect himself from this dangerous situation. He continued to undermine the position of his brother Somesvara by inducing Somesvara's feudatories to desert him. Finally with the help of the Seuna, the Hoysalas and the Kadambas of Hangala, Someshwara II was defeated and Vikramaditya assumed sovereignty in 1076. He marked his accession to the throne by founding the new era called Chalukya Vikram Era.
The conflict eventually occurred in 1076 when Kulothunga launched an attack on Vikramaditya. The war began with a clash at Nangili in the Kolar district between Kulothunga and Vikramaditya. Vikramaditya's forces were defeated and were pursued up the Tungabhadra by the Chola forces with heavy fighting all the way. Kulothunga took over Gangavadi. However in 1085, Vikramaditya seized Kanchi from the Cholas and in 1088 he conquered major pats of the Vengi Kingdom. Though Kulottunga captured Vengi in 1099, the Chalukya ruler regained it in 1118 CE and retained it up to 1124. The Kadambas of Goa, the Shilaharas, the Seunas and the Pandyas of Uchangi, Chaulukyas of Gujarat and Chedi of Ratnapur were the other rulers who were subdued by Vikramaditya VI. He married princess Mailaladevi of the Kadamba family and Chandaladevi of the Shilahara family.
Vikramaditya experienced some serious troubles during the first few years of his rule. His younger brother Jayasimha rebelled and had to be quelled. More seriously his former friends the Hoysalas, who had assisted Vikramaditya in his fight against his brother, began to undermine Vikramaditya's position. The Hoysala, although professing allegiances to the Chalukya throne, steadily began go build up their power and extend their territories. Hoysala Vishnuvardhana turned on Vikramaditya in 1116 and captured territories up to Goa on the west coast and advanced up to the Krishna River in the north.
Vikramaditya dealt firmly with this situation and expelled the Hoysala from the Chalukyan territories. Vishnuvardhana had to seek refuge in a hill fortress in his country. After many battles, Vishnuvardhana submitted to Vikramaditya in 1123.
While still engaged with the Hoysalas, Vikramaditya, turned against Kulothunga. In 1115 Kulothunga recalled his son Vikrama Chola, who was ruling Vengi as the viceroy. Utilising the vacuum in the leadership in Vengi, Vikramaditya sent his general Anantapala to invade and conquer the Vengi country who conquered Vengi. Around this time, the Chalukya feudatory, Hoysala Vishnuvardhana also defeated the Cholas in the battle of Talakadu.
Having lost Gangavadi and Vengi, the Cholas were never to rise as a major power in South India. Losing Vengi severed their control over Kalinga and lower Gangetic basin as well.
For a brief time the Chalukya empire reached its zenith and included territories as vast as that of their ancestors, the Badami Chalukyas.
However, This was the beginning of the end for both the Chalukyas and the Cholas. The unending wars had exhausted both the kingdoms and the feudatories such as the Hoysalas were preparing to defeat their masters.
Perhaps no other king in Indian history has left behind as many inscriptions, all in Kannada language, as Vikramaditya VI did. Legends recount that he followed a ritual of giving away land to the needy on a daily basis. The rule of Vikramaditya, though marred by repeated battles for supremacy in the south, was a glorious era in Kannada literary history. Great poets such as Bilhana and Vijnanesvara adorned his throne. Bilhana wrote Vikramankadevacharita and was Vikramaditya's court poet. Vijnanesvara, the author of Mitakshara, was an authority on Hindu law. Kirthi Verma wrote Govaidya during this period.
Vikramaditya's long reign came to an end in 1126. His son Somesvara III became the Chalukya king.