The new logo had been developed to encourage shoppers to buy locally produced products rather than imports mainly from Northern Ireland to support farm families and jobs in the Republic, said organiser the Irish National Dairy Council (NDC).
Currently more than 20% of the milk consumed in the Republic is imported from Northern Ireland, where prices are cheaper, and with household budgets under strain this figure has been increasing.
Ten dairies and co-ops, including major players such as Avonmore, Glanbia, Dawn Dairies and Golden Vale, have signed up to use the new logo, which simply states: NDC Farmed in the Republic of Ireland. Initially, it will apply to 340 milk and cream products, with the NDC planning to extend it to cheese and yoghurt by the end of the year.
The initiative was "not a hostile move" against Northern Irish produce, insisted NDC chief executive Helen Brophy.
Instead, she claimed it was about supporting 2,200 dairy farmers in the Republic and the 2,500 processing jobs the industry provides. "The new mark empowers consumers to make informed choices," she said. "They can select products that help sustain jobs and that contribute to the national economy and to their local communities."
Research had shown, she claimed, that 70% of consumers surveyed felt it was important that the milk they bought was sourced in the Republic, while more than 80% believed a label showing the source "would be a good idea".
The 10 companies taking part in the scheme bought a total of 500 million litres of milk a year from farmers.
Meanwhile, the Irish Farmers' Association, which has been campaigning for better milk prices, has called on processors to restructure their operations so they can deliver improved returns to suppliers.