López's appearance in public life is linked to the student movement of the Seventh Ballot [es], which between 1989 and 1990 was what gave impulse to the 1991 Constituent Assembly of Colombia.

She has been a consultant to the United Nations and has written for several media outlets in the country such as the Caracol Radio program Hora 20, the portal La Silla Vacía [es], the newspaper El Tiempo, and the magazine Semana.

Controversy was stirred by her public firing from El Tiempo in October 2009 due to an opinion column she published there which criticized the paper's coverage of certain news.

[2] On 27 December 2016, Senator López formally announced her intention to become president of Colombia in the 2018 elections, thus becoming the first pre-candidate of the Green Alliance party.

On 14 September 2017, the national congress of the Green Alliance was held to announce the results of a nationwide poll to elect the party's presidential candidate, with Claudia López winning.

[12] López began to gain notoriety after publishing a series of reports on anomalies in regional election processes on the Semana magazine website.

[14][15] In an October 2009 incident which caused controversy and debate on freedom of expression and of the press in Colombia, López was publicly dismissed from the newspaper El Tiempo after her regular Tuesday column in which she criticized how the paper had covered information related to the Agro Ingreso Seguro [es] scandal.

"[17] In 2011 a criminal proceeding was resolved in López's favor, after ex-president Ernesto Samper denounced her for insult and defamation for linking him to the Mafia in a column in El Tiempo.