Attorney General Kamala D. Harris gave notice that she will appeal last month's ruling, which barred California from enforcing its ban on selling fatty goose or duck liver produced out of state. The ban took effect in 2012.
A Hermosa Beach restaurant called Hot's Kitchen, and foie gras producers in New York and Canada challenged the ban. The judge ruled state law doesn't trump federal poultry regulations.
It remains illegal for California farmers to force-feed birds, which is how the delicacy is made.
The restaurant and foie gras producers said they are confident the ruling will be upheld.
"The decision was based on the simple fact that, in the field of meat and poultry, federal law is supreme. California does not have the right to ban wholesome, USDA-approved poultry products, whether it's foie gras or fried chicken," said a statement released by attorney Michael Tenenbaum.
Animal rights groups had called on Harris to appeal and applauded the decision.
"In a civilized society, it is our moral obligation to protect all animals, including ducks and other farmed animals, from needless cruelty and violence," said a statement from Nathan Runkle, founder of the group Mercy for Animals.
"The people of California clearly have the right to prohibit the sale of a product that is the result of abject animal abuse" Runkle said.