Pablo Ordejón is the leader of the Theory and Simulation Group at the Catalan Institute of Nanoscience and Nanotechnology (ICN2), where is also the director since 2012.

His research is focused on the development of efficient methods for electronic structure calculations in large and complex systems, based on first-principles methods such as SIESTA. He maintains frequent collaborations with industrial laboratories on the simulation of material processes at the atomic level. He is a co-founder of the spinoff company SIMUNE.

He has published more than 200 scientific articles, which have received nearly 30,000 citations (h-index of 60). He became a fellow of the American Physical Society in 2005, and received the Narcis Monturiol medal from the Catalan Government in 2018.