Arena BLM were chosen following a three-way pitch and will begin working with Mirror Group in the new year.
Pedro Avery, Managing Director, Trading & Engagement of Arena BLM, said: "We are delighted to be working with the Mirror Group and are thrilled to be partnering with them as they continue to build and evolve their trusted and well-respected brand."
Lorraine Fraser, Director of Marketing, Trinity Mirror Nationals, said: "Following a competitive pitch process we appointed BLM as we were highly impressed with their insights, strategy and creative thinking. We look forward to working in partnership with BLM to take our media planning to the next stage."
