The Sibley County Attorney's Office became a full-time county attorney's office as of December 1, 2018. Donald E Lannoye was appointed as the Sibley County Attorney on October 12, 2021. He replaces David E Schauer, the longest serving Sibley County Attorney in history, who retired on October 11, 2021. Donald Lannoye has been with the Sibley County Attorney's Office for over 19 years.

Under the direction of the County Attorney, the office is responsible for providing necessary legal representation in criminal matters, civil matters, juvenile matters, and child protection matters; providing representation to county departments and legal advice concerning county legislative matters; and providing assistance and support in law enforcement training.

The physical location of the office is on the Second Floor of the Courthouse Annex.