Wigneswaran, 73, took oath before President Mahinda Rajapaksa at a function held at Temple Trees, the presidential house.
Wigneswaran, a former Supreme Court judge, was nominated as the chief minister following the landslide victory of the country's main Tamil party, Tamil National Alliance (TNA), at the elections held on September 21.
On October 1, Northern Province Governor Maj Gen (retd) G A Chandrasiri appointed Wigneswaran to the post. Prime Minister D M Jayaratne and cabinet colleagues, Governor Chandrasiri, TNA leader R Sampanthan and several parliamentarians attended the function.
Many TNA members and supporters of the newly-elected chief minister of the Tamil-dominated province were against him being sworn in before the President.
In the run up to the Northern Provincial Council polls, the campaign was marred by claims that the President deployed troops to intimidate minority Tamil supporters and candidates and scare off voters on polling day.
Wigneswaran, 73, took oath before President Mahinda Rajapaksa.
The TNA won 30 out of 38 seats in the elections, which was the first in the war-torn region since the councils were formed 25 years ago.
Wigneswaran, who has been a magistrate and a judge of the District Court, High Court, Court of Appeal and Supreme Court of Sri Lanka, will meet External Affairs Minister Salman Khurshid in Jaffna tomorrow.