Polini has been hired as global comms director. The move comes after Greenpeace International executive director Gerd Leipold admitted that it needed to focus on achieving 'deep change', rather than 'being radical for radical's sake'.
Leipold said Polini - who worked as a journalist and TV producer before her seven-year stint at Mars - would bring valuable knowledge of the commercial sector's approach to global communications.
'Her background gives us an insight into today's 24/7 media, and she has a unique understanding of comms on a global scale,' said Leipold.
'She also has a keen interest in environmental issues.'
Reporting to Leipold and leading a team of 20 from Greenpeace's Amsterdam HQ, Polini said her role has an external comms focus.
'Greenpeace does a huge amount of scientific work, but is not as engaged with the scientific community as it could be,' said Polini. 'It is important to raise the organisation's profile.'
Polini will try to bolster the NGO's 2.8 million strong supporter base with a younger audience.