Prior to his coronation, Sri Vikrama Rajasinha was known as Prince Kannasamy. He was a member of the Madurai royal family and the nephew of Sri Rajadhi Rajasinha. He succeed his uncle as the King of Kandy in 1798 at the age of eighteen.
There was a rival claimant to succeed Sri Rajadhi Rajasinha, the brother of Queen Upendramma, who had a stronger claim. However, Pilimatalawe, the first Adigar (Prime Minister) chose Prince Kannasamy, reportedly with deep seated plans to usurp the throne to set up a dynasty of his own. Sri Vikrama Rajasinha was faced with numerous conspiracies to overthrow him and reigned through one of the most turbulent periods in Sri Lanka's history.
During his time, the British who had succeeded the Dutch in the Maritime Provinces had not interfered in the politics of the Kandy. But Pilimatalava, the first Adigar of the king, started covert operations with the British to provoke the King into acts of aggression, which would give the British an excuse to seize the Kingdom. The Adigar manipulated the king into beginning a military conflict with the British, who had gained a strong position in the coastal provinces. War was declared and on March 22, 1803 the British entered Kandy with no resistance, Sri Vikrama Rajasinha having fled. The adigar massacred the British garrison in Kandy in June and restored the king to the throne. Pilimitalava plotted to overthrow the king and seize the crown for himself, but his plot was discovered, and, having been pardoned on two previous occasions, he was executed.
The disgraced adigar was replaced by his nephew, Ehelepola, who soon came under suspicion of following his uncle in plotting the overthrow of Sri Vikrama Rajasinha. A rebellion instigated by Ehalepola was suppressed, after which he then fled to Colombo and joined the British. After failing to surrender (after 3 weeks of notice), the exasperated king dismissed Ehelepola, confiscated his lands, and ordered the imprisonment and execution of his wife and children. A propagandised account of the execution was widely circulated by sympathisers.