The 2017–18 National League 2 South is the ninth season (31st overall) of the fourth tier (south) of the English domestic rugby union competitions since the professionalised format of the second division was introduced. On 5 May 2018 Chinnor would join Cinderford in the 2018–19 National League 1 after they defeated 2017–18 National League 2 North runners up Sedgley Park 40–31 in the promotion play-off game played at Kingsey Road.