Glock had been a non-executive director of Miroma since November 2009. He will chair the management board, which consists of founder and chief executive Marc Boyan, and will be responsible for spearheading the company’s next phase of growth.
Before he retired in 2009, Glock worked at P&G for 23 years, most recently as global head of media and communication from 2001. For the past four years, he has also served as president of the World Federation of Advertisers.
Glock said: "I have been hugely impressed at how Miroma has been able to pioneer new ways of bartering, enabling their clients to maintain, and extend, their advertising capabilities by using their products and services.
"I look forward to helping the business expand further, particularly at this time when brand owners need to constantly review ways they can maintain their advertising spends and add real value."
Miroma claims to have brokered more than £100m worth of trades since launching seven years ago.
Boyan said: "Bernhard is one of the world's best marketers, and his ability to maximise advertising budgets will be invaluable to the business."