Rochet was local Party secretary in Lyon, then joined the central leadership in Paris; from 1936 to 1940, he was a communist representative in the lower chamber (the Third Republic equivalent of today's French National Assembly), elected in Colombes-Nanterre.

In 1943, after joining the Free French Forces, he represented the communists in London and was elected to the provisional legislative body in Algiers.

The problem he faced as general secretary was the balance between a needed rejuvenation of the PCF structure and maintaining an orthodox Marxist-Leninist ideology.

In consequence, he publicly stated his disregard for the leftist movement of May 1968, while later in the same year he had to deal with the Soviet crushing of the Prague Spring (when he tended to be favorable to the latter).

During the last portion of his life, Waldeck Rochet turned towards Roman Catholicism, publicly displaying devotion for The Virgin, an attitude which led several of his comrades to consider that he had become insane.