When Walker was in fifth grade, his family moved to Dover-Foxcroft, Maine, where his parents owned a hardware store and travel agency.

For approximately thirteen years he handled personal injury and products liability claims for insurance companies.

[3] Walker was nominated to the state district court by Governor Paul LePage on February 7, 2014,[4] and his appointment was unanimously confirmed by the Maine Senate soon thereafter.

[9] He was nominated to the seat vacated by Judge John A. Woodcock Jr., who assumed senior status on June 27, 2017.

[15] Walker rejected challenges to Maine's ranked-choice voting system by former Republican U.S. Representative Bruce Poliquin, who was seeking to have ranked-choice voting declared unconstitutional in order to initiate a new election after narrowly losing his seat to Jared Golden.

[3] He was appointed by Governor Paul LePage in 2012 to serve on the Board of the Combat Sports Authority of Maine.