Speaking to Adweek, Keith Weed explained that this was "a way of telling consumers that any product with the U is the right choice for the planet".
Unilever, which spent $7.6bn on brand and marketing initiatives last year, has set itself the strategic goal of doubling the size of its business while simultaneously reducing its environmental impact.
The Unilever Sustainable Living Plan, established by Weed and CEO Paul Polman in 2010, underpins the approach with each of the company's product divisions required to add social purpose to its brand positioning.
"Our brands that most engage with our sustainability and social purpose plan are growing faster," Weed said, pointing to evidence that there has been a 10% annual increase in sales among those brands over the past three years.
As part of its mission to encourage people to associate sustainability with the Unilever logo, the company launched its first TV ad for the corporate brand last October.
Featuring images of Martin Luther King and Mahatma Gandhi alongside young people giving speeches about fighting child hunger, the ad closes with the U logo as well as those of some of Unilever's leading brands, such as Lipton tea, Hellmann's mayonnaise and the Dove beauty brand.
Shown in the US, the UK, Brazil, India and Indonesia, the ad offers an emotional "explanation of what our U logo means", Weed explained.
Turning to the possibilities offered by mobile, Weed said marketers now have a "massive opportunity" to use mobile to talk to people as individuals with access to real-time data.
However, when asked whether the efficiencies offered by mobile could lead Unilever to spend less on media, Weed said that was an unlikely development.
"I'm a great believer in building the brand, so my goal is always to reach more people," he said. "Instead of trying to reach the same number of people with less money, I look at reaching more people with the same money."
Data sourced from Adweek; additional content Warc staff