He previously served as the director of operations, training, and force development of the United States Space Command.

He originally planned to enter the United States Air Force Academy, but upon visiting the campus, he felt he preferred "a little more of the traditional 'college' experience."

After commissioning he served as a Gold Bar Recruiter in Rutgers University at New Brunswick, New Jersey with the Air Force Reserve Officer Training Corps Detachment 48.

From 1998 to 2000, he served as weapons and tactical flight commander of the 2nd Space Warning Squadron at Buckley Air Force Base, Colorado.

After that, he was assigned as executive officer with the 21st Operations Group at Peterson Air Force Base, Colorado, for over a year.

[3] Miller was reassigned to the Pentagon in 2011 as a military assistant to Erin C. Conaton, who at that time was serving as the under secretary of the Air Force.

After his second command tour, he was stationed to Iraq as a senior advisor to the Prime Minister’s Office and Ministry of Interior.

He was tapped by General John W. Raymond to lead a task force on conducting detailed planning and implementation for the reestablishment of the United States Space Command.

[5][3] In January 2020, Miller was assigned as senior military assistant to the Secretary of the Air Force Barbara Barrett.

[3] In April 2021, Miller was nominated for transfer to the United States Space Force and promotion to major general.

While he waited for confirmation, he was temporarily assigned as special assistant to the vice chief of space operations while stationed at Peterson.