Miles' suspension will begin with the first game of the 2008-09 regular season for which he is eligible and physically able to play. Miles has missed the past two NBA seasons because of knee injuries. He has averaged 10.6 points and 5.2 rebounds in his career.
The 26-year-old was selected third overall by the Los Angeles Clippers in the 2000 draft.
He signed with the Celtics last month.