He studied at two Academies of Fine Arts – first in Warsaw, then he moved to Katowice, where he attended the branch of the Kraków Academy of Fine Arts. In 1961, he obtained his diploma in graphic design.
In the beginning of his professional career Lenk designed posters, book covers, books and magazines. While in Paris, he designed the Jeune Afrique weekly and the book Mexico 68 about the Sport Olympics of that year. Having returned to Poland, Lenk continued to design periodicals, including Polish Art Review, Problemy, and Ilustrowany Magazyn Turystyczny. He was the art director and designer of the acclaimed weekly Perspektywy.
The 1960s in Poland were a period of increased interest in graphic design. In 1973 the Typography and Publication Design Studio was created at the Academy of Fine Arts in Łódź. Lenk was its head from its creation to the moment he emigrated to the US (1982). He constructed his syllabus basing on his own experiences, but also drew inspiration from foreign institutions, such as, for example, the School of Design in Ulm, Pratt Institute in New York. For his work, considered pioneering in Poland, he was awarded the Prize of the Ministry of Culture and Art.
In 1982 Lenk was invited to work as visiting professor at the Rhode Island School of Design in Providence, US. In 1984, having won a competition for a full professor position, he started teaching at the Graphic Design Department. He taught at RISD until he retired in 2010.
He first started working on information design at RISD by coincidence. As visiting professor he was asked if he could add such a class to his schedule. Lenk accepted the proposition. While teaching, he went deeper into the subject and it became his passion. His program of teaching 'Diagrams, Charts and Graphs' class and the results of the students’ work were presented in the professional magazine Graphis (No 238) in 1985.
In 1990, Krzysztof Lenk, together with Paul Kahn, founded the studio Dynamic Diagrams, Consultants in Visual Logic (DD), with the office in Providence and then also in London. Under his creative direction it became one of the most specialised studios at the time, famous for its innovative methods of planning and visualization of large and complicated information structures (for internet, among other media). The list of Dynamic Diagram’s clients includes IBM, Microsoft, Yale and Harvard Universities, the Holocaust Museum in Washington DC, Musée des Arts et Métiers in Paris, American Medical Association, Siemens Nixdorf, Nature and Science magazines, Netscape, and Samsung Electronics in Korea. In 2001 Lenk, together with Paul Kahn, wrote the book Mapping Web Sites, which was translated into five languages.