Tarrant Keyneston is a village and civil parish in Dorset, England. It is situated in the Tarrant Valley, southeast of Blandford Forum. In the 2011 census the parish had 152 dwellings, 145 households and a population of 310.
On the hills northwest of the village are the earthworks of Buzbury Rings (or Busbury Rings), the remains of an Iron Age and Romano-British fortified encampment or settlement, described by Sir Frederick Treves in 1905 as "a circle of entrenchments, composed of a stout vallum and a ditch".
Almost all of Tarrant Keyneston parish is within the Cranborne Chase and West Wiltshire Downs Area of Outstanding Natural Beauty (AONB).