The crews have been working closely with the Department of Conservation to control the fire in the Ka Whata Tu O Rakihouia Conservation Park (Clarence Valley).
Fire and Emergency was alerted to the blaze just after 6pm on Wednesday, which covers about 296ha.
A spokesperson said on Friday: "The fire is fully contained and under control. Firefighters have been back out to the site this morning to mop up.
"Following further mapping this morning, the confirmed size of the fire is 296.5ha.
"A fire investigator has gone to the site today to undertake an investigation into the cause of the fire. This investigation is expected to take some time to complete.
"We will continue to work closely with the Department of Conservation and this will be our last formal update.
Six people were initially evacuated from the area and a DOC hut at Goose Flat has been damaged.
