Born at Pest, Hungary, into a Hungarian noble family. Married Eleonora Dedinszky on January 6, 1833. They had six children. The family came into disfavor and Agoston went to America in March 1840.

He went to Wisconsin and purchased a large tract of land on the west bank of the Wisconsin, River. He founded a town named Szepta, Haraszthy, Westfield and finally Sauk City. He planted grapes on the east side of the river and built the second oldest winery in the United States.

In March of 1849 he took his family to California where he planted grapes near San Diego. He was elected sherriff of San Diego County in 1850. Later he was elected to the California State Assembly in September, 1851.

He formed a partnership for the Eureka Gold and Silver Refinery near San Francisco.

Originally hired as assayer in April 1854. Employed as Melter and Refiner at the San Francisco Mint after August 1855. He was suspected of embezzling $151,550 in gold and indicted in 1857. He was fully exonerated by February, 1861.

In 1856 he bought a vineyard near Sonoma that he named Buena Vista. In 1862 he was elected president of the California State Agricultural Society. In 1863 he organized the Buena Vista Vinicultural Society.

In 1868 he moved to Nicaragua to develop a sugar plantation.

He died in Cortina, Nicaragua. He disappeared on a river on his property and his body was never found.

Melter and Refiner at the San Francisco Mint.