A NSW father found guilty of procuring his 12-year-old daughter for sex by facilitating her "marriage" has been sentenced to at least six years in prison.

The 63-year-old, who can't be named, held an Islamic ceremony at his NSW home in January last year in which his daughter "married" a 26-year-old man.

The couple later had sex at a motel and twice at his home.

"(The man) failed in his duty to his daughter," Judge Deborah Sweeney told the Downing Centre District Court.

Following a judge-alone trial, the father was in April found guilty of procuring a child aged under 14 for unlawful sexual activity and being an accessory before the fact to a serious indictable offence.

The father wanted to stop his daughter from committing a sin and believed she had to be married before being sexually active.

Concerned his daughter was developing a sexual interest in boys, and particularly the man she later married, the father arranged for the pair to meet and exchange phone numbers.

The 'wedding' was held at the father's home soon after.

Following the Islamic ceremony they went to a hotel and had sex.

A week later a room was prepared at the father's home and the couple had sex there twice.

On the father's recommendation, they didn't use contraceptive pills or condoms.

At 13, the girl suffered an ectopic pregnancy.

The man wouldn't have had sex with the 12-year-old had they not been married, and they would not have been able to marry without the father's consent, Judge Sweeney said.

She added that their religious beliefs did not justify what happened.

"They were linked in the purpose that (the man) would have sex with his daughter," she said.

Dressed in prison greens, the father sat in the dock while hearing he had been sentenced to a maximum of eight years in prison.

He will be eligible for parole in November 2020.