Iain McKerrell, who was jailed in 2006 for raping a baby, also pleaded guilty to sexually abusing an eight-year-old girl.
McKerrell, 47 , of High Street, Johnstone, raped the girl five or six times between the ages of nine and 11, when he baby-sat her at his then home in Shortroods Road, Paisley between December 2000 and June 2003.
The High Court in Glasgow heard his terrified victim was crying and shaking.
The girl did not report the rapes until last year.
The court heard that he also sexually abused an eight-year-old girl with learning difficulties on February 2 or 3, 2002.
When police initially confronted McKerrell about the rape and sexual abuse he told them: "I don't know anything about this."
McKerrell was jailed for 13 years in 2006 for the rape of a baby girl over a four-year-period. The sentence was subsequently reduced to nine and a half years on appeal.
He was out on licence for this offence when the new allegations against him were made.
Judge Lady Rae deferred sentence on McKerrell until June 26 at the High Court in Edinburgh and also placed McKerrell on the sex offenders' register.