Mohammed Abbas, 23, of Broad Street, Barry was found guilty of several counts of raping a girl under the age of 13.
The charges related to offences committed over a number of years, a jury at Merthyr Tydfil Crown Court was told.
Abbas had denied the rape allegations, entering not guilty pleas before standing trial.
However, jurors returned guilty verdicts on the rape counts.
The defendant had previously admitted a charge of sexually touching a girl under the age of 13.
Judge Jeremy Jenkins ordered that Abbas be made subject to the sex offender notification requirements and report to his local police station.
The defendant was granted conditional bail ahead of sentencing.
Conditions include a prohibition on contacting the complainant or any prosecution witnesses, either directly or indirectly.
A pre-sentence report has been ordered.
Abbas is due to appear before Cardiff Crown Court on July 30 for sentencing before Judge Jenkins.
The complainant is entitled to lifelong anonymity under the Sexual Offences (Amendment) Act 1992 and cannot be identified.
