The 2009–10 season was Clube Desportivo Nacional's 8th consecutive season in the Primeira Liga and 99th year in existence as a football club.

In addition to the domestic league, Nacional participated in this season's editions of the Taça de Portugal, Taça da Liga and UEFA Europa League.

Note: Flags indicate national team as defined under FIFA eligibility rules; some limited exceptions apply.

Players may hold more than one non-FIFA nationality.

Source: [1] Source: Competitions Source: Competitions