Impact Leaders: Interview with Matt Longley on B Corp and Sustainability Leadership

Matt is CEO of Mobsta, a boutique media ad tech company specialising in audience targeting. Matt started his career client-side, then moving to work in multi-national media agencies, before joining Mobsta. He's a proponent of "good growth", having seen the full breadth of where bad growth takes a company, in multiple environments. For Matt, good growth is where you build a more responsible and accountable company, aware of your impact on the world around you, bringing customer loyalty and team empowerment.

A B Corp-certified company, Mobsta has consistently ranked among the best digital media companies to work with, according to industry surveys (IPA), and focuses its efforts on delivering targeted ad campaigns that reduces wasted media and greenhouse gas emissions compared to traditional digital advertising.

Find Matt on LinkedIn here.

Toby (ZeroBees): Matt, always great to chat with you. Let’s start with your background. What led you to Mobsta, and why is B Corp important to you?

Matt (Mobsta): My career started in the civil service, specifically in the marketing team. I was passionate about public service, including working for the Electoral Commission, promoting democracy. Eventually, I moved into the media industry, handling government media buying and working across different agencies.

When I joined Mobsta, I was looking for a company that I could help shape into a business I truly wanted to work at—one with great working practices and a sustainable outlook on the future. And around 2019, the push toward Net Zero really started gaining momentum too.

It’s been a long journey, but six years later, we’ve made huge progress.

B Corp is important because it provides a structured framework and external verification to ensure we’re doing the right thing. It’s the most recognized and rigorous standard out there for responsible business.

Toby: Can you walk us through Mobsta’s journey to becoming a B Corp? What motivated the company to pursue certification?

Matt: I knew I wanted to do it back in 2019, when B Corp was still fairly new in the UK. But we didn’t apply until 2021. From application to verification, it took 11 months, but we had already done a lot of groundwork beforehand.

Early on, we completed the B Impact Assessment and scored lower than we wanted. But it helped us understand what needed to change. We made small but significant changes, like becoming a Real Living Wage employer and thinking more about apprenticeships.

When we reassessed, we scored around 80, which was enough to certify, but we wanted to do more—improving governance, increasing our community engagement, and making a bigger impact locally. That led us to partner with organisations like the House of St Barnabas, which supports people experiencing homelessness. We employed some individuals who had a background of homelessness too, which was a big step for us too.

We finally submitted for B Corp in 2021, and scored 94.7 when we certified in 2022. One challenge was our environmental sustainability score, as we didn’t control our office space, so we decided to move to an office where we had more control over emissions. It’s been a long journey, but absolutely worthwhile.

Toby: How did you get buy-in for B Corp certification at Mobsta, both from leadership and across the company?

Matt: The first step was getting our two founders on board. At the time there were less than 1000 British B Corp companies and very few in the media industry. So it was fairly easy to convince them that being a B Corp would give us an early competitive advantage and we could be a better kind of company without it impacting our bottom line.

For the wider team, we took the time to explain what B Corp is and why external verification matters. Once people saw that it wasn’t just a badge but something that would shape how we operate, it was a fairly easy sell internally.

Toby: What are some of the biggest sustainability challenges in digital media, and how is Mobsta addressing them?

Matt: When we started working with ZeroBees in 2021, there was barely any data on sustainability in media from a carbon perspective. The industry was only looking at end-user device emissions, which ignored a huge part of the problem.

One of the biggest challenges now is the bid-win ratio—the inefficiency of bidding for digital ad space. It’s a physical challenge to reduce and, more importantly, to get clients to care. Agencies are largely on board, but many brands are, understandably, still heavily focused on sales.

We’re tackling this by running case studies and experiments to prove you can reduce emissions without hurting performance. One of our biggest successes was with Heineken—we optimized their campaign for low carbon and actually improved performance.

We’re also working on engaging sustainability teams at brands, as many aren’t yet thinking about carbon in their media campaigns. There’s interest at the board level, but there’s still a panic about potential impacts on profit and sales.

Toby: You’ve made significant strides in reducing digital supply chain emissions. How did you approach this, and what levers did you use?

Matt: Working with ZeroBees early on, we identified three key levers: better targeting (fewer but more relevant ads), creative selection (choosing lower-carbon formats), and streamable ads through SeenThis. Many video ads use carbon whether they’re watched or not, so streaming rather than downloading makes a big difference.

Now, we offer carbon as a standard campaign metric—alongside viewability and accessibility—so clients can make informed choices while still maintaining performance.

Toby: What’s one of the most impactful changes you’ve made as part of your B Corp journey?

Matt: Being one of the first B Corps in media gave us a stronger voice in the industry. It provided credibility, and other companies have since followed suit.

Mobsta’s role in the industry has been to help others catch up. We’ve been able to drive momentum, ensuring sustainability becomes a bigger part of the conversation.

Toby: Has becoming a B Corp changed how clients, investors, or partners perceive Mobsta?

Matt: At first, it didn’t have a big impact on ROI. But as we approach our three-year anniversary, we’re seeing that being an early adopter has built trust.

Our revenue has doubled in the last two years—not purely because of B Corp, but because it embodies everything we do. It also helped us attract top talent. We hired seven interns last year who explicitly wanted to work at a B Corp. That’s a huge shift in the industry.

Toby: What are your top tips for businesses considering B Corp certification?

Matt: Do the assessment as soon as possible. Even if you don’t plan to certify, it’s an incredible tool for understanding your business and where you can improve.

Then, set simple goals to address gaps. One area we improved on was age diversity. We realized we lacked younger employees, so we focused on bringing in more Gen Z talent.

Toby: Looking ahead, what’s next for you and Mobsta?

Matt: AI is our next big focus. We need to understand AI-related emissions and how they impact our industry. Our audience platform is already reducing the time spent on data entry—now we need to quantify the emissions impact of that efficiency.

We also want to push the industry toward streaming ads rather than downloading them. If every media company did that, the carbon savings would be huge.

Toby: Matt, thanks so much for sharing your insights. It’s exciting to see how Mobsta is leading the way in sustainable digital media.

Matt: Thanks, Toby. Always great to chat!

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This series of interviews is in support of our mission to accelerate sustainability and decarbonisation across SMEs, NGOs and value chains. By sharing experiences, lessons learned and tips and tricks to embedding sustainability, we can all learn how to improve more, faster.

ZeroBees (certified B Corp) are experts advisors for sustainability and B Corp. From measuring and reducing greenhouse gas emissions to full support for B Corp assessment and re-certification, communication and impact reporting, we're here to help you navigate what's important and how to leverage your strengths. Book a call with us today.