A southern Tasmanian man who prostituted a 12-year-old girl to more than 100 clients will spend at least eight years in jail.

Gary John Devine pleaded guilty to procuring sex with a young person and receiving a fee from child prostitution.

The court heard that last August and September the 51-year-old placed newspaper advertisements for the girl's services, saying she was 18 years old and new in town.

Devine made bookings and took a cut of the proceeds, charging $100 per half hour and an extra $50 if the man did not wear a condom.

The girl worked for two nights from a Hobart hotel and for a further four weeks from Devine's house and at the home of a client.

The court heard that the girl has since been treated for sexually transmitted diseases, no longer attended school and had been spurned by her friends.

In her victim impact statement she said she would have to live with what was done to her for the rest of her life.

Justice Evans says some of Devine's many prior convictions suggested he was contemptuous of females.

They included assaulting a pregnant woman.

He sentenced Devine to 10 years in jail with a non-parole period of eight years.