Berthold was born Berthelemi Antoine Marthias Bertolla de Moncenigo near Trent, Tyrol, Italy, in 1780. When Napoleon invaded Italy, Bartholomew joined the opposition and was wounded in battle. After the French conquered Italy, he left his homeland and arrived in the United States in 1798.
At that time, he anglicized his name to Bartholomew Berthold. Courteous and well-educated, he was fluent in French, Spanish, German, Latin, and Italian. After a short stay in Philadelphia, Pennsylvania, he settled in Baltimore, Maryland, but in 1809 he moved to St. Louis, Missouri. Here, along with Rene Paul, he engaged in the mercantile business. In 1811 he married Pelagie Chouteau, the only daughter of Major Pierre Chouteau, Sr., and the couple would eventually have seven children.
He then partnered with his brother-in-law, Pierre Chouteau, Jr., and conducted a successful business for several years. Later, he and Chouteau, John P. Cabanne, and Bernard Pratte became associated with John Jacob Astor in the American Fur Company. The business was very profitable, and Berthold became one of the wealthiest citizens of St. Louis. He died in St. Louis, Missouri, on April 20, 1831, at the age of 57. His widow survived him for 44 years, dying in 1875 at the age of 85.