He was the son of a Russian Jewish emigrant, David Lazareff, and an Alsatian Jew, Marthe Helft.
He was passionate about newspapers from his childhood, even running a family paper called Le Journal des Bibis.
In 1928, he joined Paris-Midi, where he brought in his friends Joseph Kessel, Roger Vailland and Charles Gombault.
Under Lazareff's leadership, the paper reached a daily circulation of 2.5 million, a record for the French market.
After the liberation of France, he came back to Paris in 1945 where he led a new evening paper titled France-Soir with the same success he had achieved at Paris-Soir.