It is alleged he abused two girls known to him, the first between 1982 and 2001 with the first offence occurring when she was just five-years-old.
The second girl was seven-years-old when she was first sexually assaulted between July 2017 and February 2018.
The man is currently in prison and has been charged with five counts of sexual penetration of a child who is a lineal relative, two counts of indecent dealings, 10 counts of indecent dealings with a child under 14 and three counts of unlawful and indecent assault.
He is due to appear before the Geraldton Magistrates Court today.
Police have asked anyone with further information to call Crime Stoppers on 1800 333 000 or make a report online.
This article originally appeared on PerthNow.