After being influenced by her primary school teacher at Public School No. 3 in Valparaíso, she joined in 1933, at the El Tofo iron mine, the ranks of the newly founded Socialist Party of Chile.
In 1937, she represented the Ovalle section of her party at the Leftist Convention that proclaimed Pedro Aguirre Cerda as a presidential candidate.
Between 1939 and 1943, she was a leader of the Confederation of Workers of Chile and national leader of the Socialist Youth. From 1941 to 1947, she participated in the Central Committee of the latter organization and served as general secretary of the «Comité Patria y Pueblo».
Around 1943—at the age of 23—she was elected the first female councilor for Santiago, a position she held until 1947. At the same time, she served as director of the Municipal Theater, interacting with prominent artists, including Claudio Arrau. The following year, in 1948, she became a national advisor for the Workers’ Accident Insurance Fund. In her professional life, she worked for the National Health Service (SNS) and served as a public relations officer for the hospital area in the southern sector of the SNS. Between 1955 and 1960, she worked for the Social Security Service.
In the 1965 parliamentary elections, she was elected deputy, and she was re-elected in the 1969 and 1973 elections.
After the 1973 military coup, she went underground, seeking refuge in private homes, and later took asylum at the Colombian Embassy. In April 1974, she went into exile, spending the first year in Colombia. The following year, she moved to Caracas, Venezuela.
In 1987, after fourteen years of exile, she was allowed to return to Chile. Upon her return, she committed herself and actively participated in the restoration of democracy.
In 1989, she ran again for a seat in the Chamber of Deputies for the 1990–1994 term, representing District No. 24 (communes of La Reina and Peñalolén, in the Santiago Metropolitan Region), but was not elected. She ran again in December 1994 for the same district, but was once more unsuccessful.
Lazo was a member of the Central Committee of her party in 2008. Nevertheless, she died on 18 August 2008, in Santiago.
