Russian businessman, philanthropist, and vigilant fighter for the rights of his Jewish co-religionists in the teeth of persecution by the Russian government. His father was the philanthropist Joseph Günzburg. His son David became a prominent Orientalist and bibliophile.

For a time, Horace Günzburg ran the banking firm that his father had founded, but he closed it during a financial crisis, even though it was solvent. In 1863, along with his father, he founded the Society for the Promotion of Culture Among the Jews of Russia, a highly successful organization that disseminated Jewish culture in the Russian language; he became president of the society upon his father's death in 1878 and almost single-handedly financed it, sponsoring translations into Russian of such classic works as Heinrich Graetz's Geschichte der Juden von den ältesten Zeiten bis auf die Gegenwart (“History of the Jews from Oldest Times to the Present”) and the Bible. In the early 1870s, again like his father, he was created a baron.

In 1870 and again in 1877, as a representative of Russian Jewry, Günzburg appeared before governmental commissions investigating the “Jewish question.” In 1882 he chaired a Jewish congress called in response to the government's infamous May Laws of that year, which further confined Jews to the overcrowded ghetto known as the Pale of Settlement.

Günzburg not only attempted to ameliorate governmental oppression but also actively supported organizations working in other ways in behalf of the Jews. He assumed successively the offices of chairman of the central committee of the Jewish Agricultural Society (1893) and the presidency of the board of directors of the Jewish Agricultural Farms in Minsk (1901). In 1908 he was a cofounder of the Russian Jewish Historical Ethnographic Society in St. Petersburg.

Günzburg's activities were not confined to helping the Jews. The government frequently called upon him for advice on laws dealing with the Stock Exchange and other major business institutions, and he was a large contributor to the building of the Stock Exchange Hospital, a trustee of the School of Commerce of Tsar Nicholas II, and an alderman of St. Petersburg.