1999–2000 Segunda Divisão B

The 1999–2000 Segunda Divisão season was the 66th season of the competition and the 50th season of recognised third-tier football in Portugal.

Overview
The league was contested by 58 teams in 3 divisions with AD Ovarense, FC Marco and Nacional Funchal winning the respective divisional competitions and gaining promotion to the Liga de Honra. The overall championship was won by FC Marco.