Upon the death of his father in 1810, William Duckett Bowie was made the executioner of his will which increased his wealth significantly and his uncle, Daniel Bowie bequeathed to him all of his land upon his death as well which combined, made him one of the wealthiest planters in Prince Georges County.
In 1830, he and his uncle Walter Bowie Jr. were appointed by the Governor Thomas King Carroll as members of the Levy Court for Prince Georges County. In 1838 and 1839 he was nominated by the Democrats for the state Legislature but defeated by his cousin Thomas Fielder Bowie the Whig candidate. in 1840, he overcame the large Whig vote and was elected to the Maryland House of Delegates in which he served two terms. After that, he beat the Whig leader Robert Bowie of Mattaponi, Maryland for the Maryland Senate seat. He was re-elected at the end of his first term.
On January 7, 1854, William Duckett Bowie married his first wife's half-sister, Mary Black West. They had three girls, Harriet Oden Bowie, Mary Eliza Bowie and Laura Bowie.
After his second marriage Bowie gave Fairview to his eldest son, Oden Bowie and moved to Bellefield near Croom, Maryland which was the old Colonial home of his second wife. Bellefield had originally been the property of Patrick Sim, ancestor of Governor Thomas Sim Lee. Bowie died at Bellefield July 18, 1873 and is interred at Fairview.