Phillip Monk, 61, of Penycoedcae, Pontypridd, went on trial at Newport Crown Court accused of 23 counts of indecent assault of a person under the age of 14, relating to seven girls.
He was found not guilty of assaulting pupils at Maesybryn Primary School, near Pontypridd, between 1984 and 1995.
No evidence was offered on six similar charges relating to two girls.
He was also cleared of these.
Judge Daniel Williams formally found Mr Monk not guilty of these charges after at a hearing on Monday after being told no evidence would be offered by the prosecution.
A primary school teacher accused of indecently assaulting his pupils has been cleared of all charges.