State governor Seriake Dickson of Jonathan's Peoples Democratic Party (PDP) was re-elected for a second four-year term in office, beating former governor Timipre Sylva of President Muhammadu Buhari's All Progressives Congress (APC).
Dickson polled 134,998 votes against Sylva's tally of 86,852, returning officer Zana Akpaogu said on Sunday.
State governorship elections were held across the country in April but the vote in southern Bayelsa was put back until December 5 and then declared partially invalid due to violence in which unofficial reports said at least four people died.
Despite its resources, the small state of 1.7 million people is one of the country's poorest.
Jonathan secured some 98 percent of the vote in Bayelsa during his unsuccessful re-election bid in March.
