In 1994, he starts working at the Development and Organization section in charge of professional training for the Chamber of Commerce of Nantes St-Nazaire.
Through his teaching engagements, Guellerin has shared his expertise and knowledge with students and contributed to the academic community.
He was also a member of the jury for the Design Eleven contest, which was launched in 2010 by the (EESC) to prepare the "European Year of Active Ageing and Intergenerational Solidarity.
Created 20 years ago, Cumulus is now the largest international network dedicated solely to issues of design education, with 3,100,000 students and nearly 30,000 teachers.
The institution has developed significantly under his leadership, striving towards the professionalization of design studies and establishing relationships with businesses.
A few of the most significant steps in this development of L'École de design are: the opening of a Hypermedia section dedicated to digital products and services, in 2000, the granting of an official accreditation from the French Ministry of Higher Education in 2002 for its master's degree in Design, the opening of a spatial design section in 2005, the creation of an Apprentice Training Centre (CFA) specialized in “Industrial Creation and Innovation” in 2006, the setting up of the school's China campus in 2008 initially in Qingdao (China), and now in Shanghai (China), the launching of a graphic design option and the reorganization of the master's programs into social and economical themes in 2009.
In 2019, the opening of the "Human Machine Design Lab", will accompany the technological progress since the first “hypermedia”: technologies for speech recognition (and synthesis), images, Big Data mining and exploitation, Artificial Intelligence, robotics, Virtual, Augmented and Mixed Realities.