Mr Addison (46) joined the SDHB in December 2011 and will finish tomorrow. Chief executive Carole Heatly said the SDHB would miss Mr Addison's experience and dedication.
''He has made a real impact on the way in which the DHB communicates and has been a key member of my executive team,'' Ms Heatly said.
The SDHB has not announced a replacement.
Mr Addison said he was looking forward to starting his new venture as a consultant.
''This will give me the time to continue my interest in human rights journalism and to travel.''
Mr Addison is also a freelance journalist and founder of a human rights website.
Next month, he will return to Jordan and Turkey for three weeks, a year after visiting refugee camps there.
''I'll be going to Zataari refugee camp [in Jordan] to visit some of the families that I visited last year.
''I'll also be visiting some camps in Turkey and interviewing refugees looking to migrate.''
Mr Addison said his guide and translator would be Syrian Usama Ajjan (27), who last week was released by kidnappers after 60 days in captivity in Aleppo.
Mr Addison was a journalist for the Otago Daily Times for about two years in the 1990s.
He will continue to be based in Dunedin with his family.
