The swearing-in ceremony held on Friday was conducted by the Chief Judge of Bayelsa State, Justice Kate Abiri, at the Liberation Stadium in Port Harcourt, the Rivers State capital.
Mr Wike and his Deputy, Ipalibo Banigo, were sworn in at about 10:47am, in a ceremony that seemed to have laid to rest the controversy that preceded the swearing.
The new Governor, who was a former Minister of State for Education, told thousands of people at the stadium that the days of maladministration were over.
He further said he would ensure security of lives and property in the state, which witnessed series of attacks at political gathering and the death of some persons in the build up to the governorship election.
Mr Wike won the Governorship election of April 11, defeating Mr Dakuku Peterside, with a total of 1,029,102 votes. Mr Peterside polled 124,896 votes.
After Mr Wike won the election, there were controversies over who would conduct the swearing-in ceremony.
To end the controversy, the Attorney-General of the Federation and Minister of Justice, Mr Mohammed Adoke, on May 19 directed the Chief Justice of Bayelsa State to swear-in Mr Wike on May 29.
The directive was as a result of the existing vacuum in the office of the Chief Judge of Rivers State and the President of the Customary Court of Appeal in Rivers State.