When he dropped out of the priesthood he changed his name to "Charles" in 1820 and moved to the United States (probably at St. Louis, Missouri where he worked in the fur business with the Chouteau family).

Beaubien, hoping to open businesses away from direct Mexican control, enlisted Guadalupe Miranda, the secretary of the government, to petition for a grant of 1,700,000 acres (6,900 km2) on the eastern side of the Sangre de Cristo Mountains.

In 1843, Beaubien and Miranda signed away one-fourth of their grant to Charles Bent in exchange for help in establishing ranches along the Ponil, Vermejo, Cimarron and Rayado rivers.

Later in 1843 Beaubien applied for a 1,000,000-acre (4,000 km2)[2] grant in the San Luis Valley east of the Rio Grande and extending to the summits of the Sangre de Cristo Mountains in southern Colorado.

When Stephen W. Kearney set up government in Santa Fe, New Mexico in 1846 and established Charles Bent as governor.

In the revolt, Beaubien's son Narciso (freshly arriving from school in Cape Girardeau, Missouri), his partner Stephen Louis Lee, and Governor Bent were killed.

After Sterling Price put down the rebellion, Beaubien was the judge to overseeing the trial of his son's murderers prompting Father Martinez to accuse him of "endeavoring to kill all the people of Taos."