- "I've seen things that no training can prepare you for, that I know of. I look at the faces around me, and I know that nobody expected anything like this."
- — Private Miller.
Miller is first seen in on Makin Atoll in a Japanese base. Prior to that, Miller was part of a Marine Raider team that landed on Makin Island and was captured by Japanese forces and brought to the Japanese base. Miller witnesses fellow Marine Pvt. K. Pyle have his throat slit by a boot knife after he spat at a Japanese Officer's face. Before the Japanese could execute Miller, he was rescued by Corporal Roebuck, Sergeant Tom Sullivan and other Marine Raiders when Roebuck impales Miller's assailant in the back with his knife and Sullivan strangles the Japanese officer.
Miller and the Marines damage the Japanese forces stationed on Makin Atoll and move to the extraction point. However, Miller is knocked to the ground by an explosion and is attacked by a Katana-wielding Japanese soldier but is saved by Sullivan and is dragged onto a boat. Years later, Miller, Sullivan, Roebuck, teen recruit Polonsky and elements of the 1st Marine Division storm the white beach of Peleliu Island to make way for Allied forces. However, in the final stage of taking the beach defenses, Sullivan is killed by a Banzai Charger with a Katana with Roebuck being promoted to Sergeant. Miller and the Marines then secure Peleliu Airfield and crush the remaining Japanese forces.
Seven months later, Roebuck, Polonsky, and Miller take part in the invasion of Okinawa, the bloodiest battle of the Pacific War. Despite being low on supplies, Miller and his squad decimate the Japanese forces at Wana Ridge. Then the 1st Marine division storms Shuri Castle, the last Japanese stronghold on the island. Late in the battle, Miller's squad comes across Japanese soldiers attempting to surrender. It turns out to be a clever trick when they assault Roebuck and Polonsky who were trying to secure them (the player could choose to save either Roebuck or Polonsky). After saving Polonsky/Roebuck, Miller and the remaining Marines are engaged by numerous Japanese forces. Miller and his team are saved when the Japanese are assaulted by an U.S. fighter plane and are defeated. After the battle, either Roebuck or Polonsky hands Miller the other's dog tags, and Roebuck's voice can be heard in the background, saying that they could all go home.
- According to his birth date (August 2, 1922), he is around 20 at Makin, and around 22 at Peleliu and Okinawa.
- Miller is the support gunner for the squad.
- Miller is the squad's radioman (as seen in "Little Resistance" and "Breaking Point", with the exceptions being "Hard Landing" and levels where he uses a Flamethrower).
- In Call of Duty: World at War (Nintendo DS), a recurring character in some missions is named Pvt. Miller.
- In the opening cutscene of Call of Duty: World at War, it is revealed that Pvt. Miller had affiliations with the 34th Infantry Division which is a part of the U.S. National Guard. Either Miller was slated to be in the 34th I.D. prior to the game's release and then scrapped, or Miller's affiliation to the 34th I.D. was purposefully used by Treyarch to reveal the fact that he was briefly in the U.S. National Guard prior to joining the Marine Raiders.