Armijo was a staff attorney of Sandoval County Legal Services, New Mexico from 1976 to 1978 where she served, among others, indigent Native Americans.

In 1996, Armijo was appointed by Governor Gary Johnson to the New Mexico Court of Appeals.

While serving on the Court of Appeals, Judge Armijo authored more than 50 opinions and participated in many more.

Under her leadership, the court also worked cooperatively to consolidate the federal bankruptcy court into the Domenici federal courthouse, reportedly saving taxpayers roughly $1 million per year.

During her tenure as chief, the U.S. District Court filled eight full-time and part-time magistrate judge positions.