Emma Okah, the state commissioner for information and communications, announced this in a statement on Friday.
He said the senior advocate of Nigeria (SAN) passed on while receiving treatment in a London hospital.
He described the death as a “monumental” loss to both the state and the family.
The statement read: “It is with very deep pain but gratitude to the Almighty God that the Rivers state government wishes to announce the demise of the state attorney general and commissioner for justice, Hon Emmanuel Chinwenwo Aguma, SAN, today Friday 10th August, 2018 in a London hospital.
“Until his death, Emmanuel Chiwenwo Aguma, SAN served the state with amazing sense of responsibility, commitment, passion, competence and courage. At all times, even in his sick bed, his exemplary zeal to serve Rivers state never waned.
“Consequently, the Governor of Rivers state, His Excellency Nyesom Ezenwo Wike CON, GSSRS has approved that flags fly at half-mast for two days beginning from tomorrow Saturday 11th August, 2018 as a mark of honour to mourn the departed legend.
“Needless to say that Rivers state and indeed the nation will miss his versatility and invaluable contributions to the development of our state and Nigeria.
“This loss is monumental but we urge all people of goodwill to remember his wife, children, mother and the entire Late Chief Emmanuel W. Aguma family of Port Harcourt as well as the State in prayers.”