Stubley, former senior executive of WPP, Fast Track and Channel Four, will assist the board in the expansion of the business and focus on growing the existing sponsorship, PR and events offering.
He will also evolve the company's digital business plans and the provision of strategic advice to existing clients.
Stubley was founding chief executive of WPP-owned sport and entertainment consultancy Performance, and has been a board director at Clipper Ventures and managing partner at agency Fast Track.
He was also a partner at MEC Interaction and headed the business development department at Channel 4 for six years.
Rupert Pratt, co-founder and managing director at Generate, said: "David has an excellent track record in growing agencies and businesses across multiple regions and sectors. He is aligned with our vision and brings with him more than 25 years of experience working within television, international media, advertising, sponsorship, digital and sports rights.
"It is time for us to implement our next ten-year business strategy and grow Generate. David is well placed to assist us on this journey."
Stubley added: "Generate has an impressive service offer, strong work ethic and delivers exceptional work. I am excited by the vision for the development of the business and looking forward to working with Rupert and his team as the agency takes its next steps within the sport and entertainment industry."
Founded in 2003 by Pratt and Andy Muggleton, Generate's client portfolio consists of Ebay, QBE Insurance, ECB, Ambassador Theatre Group, Save the Children, Merlin Entertainment, Premiership Rugby, Kew the Music and Speedo.
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