Jiménez was born in Barcelona on 11 January 1971. He graduated in journalism from the University of Barcelona and began work in 1994 for "El Mundo", working as an intern on its Madrid and Society sections. In October 1998 he became the paper's first correspondent in Asia, remaining there until 2014 and covering the conflicts in Afghanistan, Kashmir and East Timor. His coverage of Tibet induced the Chinese government to ban him from returning to that country. He reported clandestinely from North Korea and was the only Western reporter to stay in Fukushima through the nuclear disaster of 2011.