The jury at Inner London Crown Court cleared the 38-year-olds who had told police they gave Anthony Benton a 'good hiding' for indecently assaulting the girl.
Benton, 42, who has a history of sexually abusing young girls, was kicked, punched and head-butted by the brothers.
'He molested my nine-year-old daughter, he deserved it,' the girl's father had told police.
Judge Dawn Freedman had told the jury: 'However much you sympathise with these defendants you must not regard their actions as anything but unlawful.'
The girl's father was acquitted of causing actual bodily harm and the uncle was acquitted of causing grievous bodily harm with intent and an alternative charge of inflicting grievous bodily harm.
The court was told Benton molested the girl after helping her father move into a new home in Eltham, south London.
Benton was found guilty of indecent assault last week and is due to be sentenced next month.Reuse content