H Yodsook, 40, was convicted on 12 counts, receiving a sentence of seven years on each, for a total of 84 years.
As he had pleaded guilty his sentence was halved to a total of 42 years. The terms are cumulative, Bangkok Post reported.
The report said that the man had forced the girl to have sex when the child's mother was out on work and threatened her not to tell anyone.
The mother later found out and pressed charges against her husband.