|High School:||Westerville North HS|
Finished first in the 50 free (19.79) and second in the 100 free (43.78) as a freshman for the Tigers. Miller set a program mark in the 100 fly (46.58) at the MPSF championship. Also set a 18.9 time in the 200 free relay split and and helped set the the program record for the 400 medley relay (3:12.15). Miller's efforts earned First-Team All Mountain Pacific Sports Federation (MPSF).
Miller placed first in the 100m fly and 50m free during his freshman, sophomore, junior year for Westerville North.
Miller is the son of Aaron and Jennifer Miller. Mason has three siblings: Maddie, Lindy, and Abbey.