The 2005–06 Serie D was the fifty-eighth edition of the top level Italian non-professional football championship. It represented the fifth tier in the Italian football league system.
^Dropped because of financial troubles; third-placed Poggibonsi promoted in its place, following renunciation of second-placed team Fortis Juventus to play Serie C2 in 2006–07.
^ abAdditional team also promoted via playoffs; see below.
^Vibonese also promoted by the Football Federation to fill Serie C2 league vacancies.
Promotion playoffs
First round
Single-legged matches played at best placed club home field