Internationally renowned, Colombo had collaborated with several European universities. At Università della Svizzera Italiana he had been professor in charge of the Media Genres and Formats course, at the Université Stendhal in Grenoble he had held the UNESCO Chair in International Communication, he had taught as visiting professor at Université Lumière in Lyon and at the Sorbonne in Paris, where he had also been a member of the Scientific Council of CELSA, the school for advanced studies in information and communication sciences. Member of the Academia Europaea. Finally, he had been a member of the selection committee of the Film, media and visual studies section.
Creator of the Research Centre for Communication and Media at Università Cattolica (OssCom), which he directed for 18 years, he had participated in research projects of national interest and collaborated with major companies and cultural institutions.
Since the beginning of his career, Colombo had been concerned with the link between digitalisation and social transformation. The result of these interests are his debut volume Gli archivi imperfetti (Vita e Pensiero, 1986), Le nuove tecnologie della comunicazione (Bompiani, 1994), written with Gianfranco Bettetini, and La digitalizzazione dei media (Carocci, 2007). In the second decade of the 2000s, he had entered the vein of critical analysis of the web with Il potere socievole. Storia e critica dei social media (Bruno Mondadori, 2013) and a series of essays on phenomena such as trolling, data control and privacy challenges. A series of empirical investigations on the links between digitalisation phenomena and generational belonging also fall into this period. By 2020, this set of experiences had converged in ‘a manifesto for a “gentle” communication’ published by Vita e Pensiero as Ecologia dei media. One of Colombo's most personal and characteristic books, Imago pietatis, lucida riflessione sul legame tra fotografia e compassione, was also published by Vita e Pensiero in 2018.
Another theme that Colombo investigated with continuity was the history of the media in Italy. He had explored the subject in depth, for example, in La cultura sottile (Bompiani, 1998), in the autobiographical Boom (Rizzoli, 2008) and in Il Paese leggero (Laterza, 2012).
On 13 November 2024, already ill, Colombo gave a crowded open lecture in the Aula Magna of Università Cattolica Milan campus in Largo Gemelli, once again returning to the theme of the relationship between high and low, elite and community culture. The text of the lecture, on the revision of which the professor worked until the last days, will be published in the coming months by Vita e Pensiero. This latest Lezione sulla cultura popolare (this is the announced title) will soon be joined by the essay Una storia in comune. Perché la cultura pop racconta chi siamo, written with Lorenzo Luporini and to be published by Mondadori in February.