Arizona Court of Appeals Judge Ann Scott Timmer is Gov. Jan Brewer's choice to fill a vacancy on the Arizona Supreme Court.
The 52-year-old Republican was one of three finalists nominated by a state screening commission.
Timmer replaces former Justice Andrew Hurwitz, a Democrat, and her appointment changes the court's partisan makeup to four Republicans and one Democrat. Hurwitz resigned in June to become a federal judge.
Brewer's three Supreme Court appointments have all gone to fellow Republicans.
Timmer was appointed to the Court of Appeals in 2000 by then-Gov. Jane Hull, another Republican.
Brewer said in a statement that Timmer embodies judicial restraint and respects the separation of powers among branches of government.
In 2003, Timmer authored a decision upholding the constitutionality of Arizona's law banning same-sex marriages.