It follows an 8% increase in April and a 15% hike in July due to increasing farm and production costs.
The new pricing will see a 500ml carton increase from 75p to 80p, while a litre will rise by 10p to £1.45.
Isle of Man Creamery said the rise was the only way to keep farmers’ businesses and the local dairy industry “viable and operating successfully”.
The retail price of milk on the island is set by the Milk Marketing Committee, which is chaired by the Minister for Environment, Food and Agriculture and includes representatives from the Office of Fair Trading and the National Farmers’ Union.
Much of the milk produced on the island is processed by the Isle of Man Creamery, which operates as a cooperative with local farmers.
Managing director Findlay Macleod said this year had been “particularly hard for both individuals and businesses” as operating costs throughout the dairy industry “increased significantly”.
He said the compound effect of “huge increases” in the costs of fertiliser, feed, fuel and power had “resulted in increased pressure on our farmer producers”.
“As a cooperative of dairy farmers it is vital that the creamery is able to pay a fair price to the farmers for their milk which takes all of these pressures into account,” he said.
The increase would “help all local suppliers and the wider dairy industry navigate these extremely trying times”, he added.