Mervyn Free lured the seven-year-old from a Queensland department store toy aisle just before Christmas last year and molested her.

The father of two has apologised for the depravity inflicted on the girl.

"I cannot imagine the pain and fear I've caused," the 27-year-old said in a statement through his lawyer on Friday.

Free had just been sentenced to eight years in prison for taking a child for immoral purposes, depravation of liberty and the indecent treatment of a child under 12.

He can apply for parole from August 10, 2021.

However, the girl's mother says no amount of punishment will make up for the trauma.

She was shopping in a Kmart store at Westfield North Lakes, north of Brisbane, in December when her daughter went to look for a toy and did not return.

The mother raised the alarm with security, who found CCTV footage had captured Free walking through the store, in a way that was described as predatory, before leading the child away.

Free took the girl to bushland and sexually assaulted her, dropping her back at the shopping centre more than an hour later.

Her mother noticed two long scratch marks down her back, which the child refused to explain. She also would not tell police.

The pedophile later told police he felt "sick and disgusting" over what he had done, Brisbane District Court Judge Julie Dick said before sentencing him.

Free, who pleaded guilty to all charges, is a pornography addict with a pedophilic disorder who was himself abused, previous court hearings were told.

Before the hearing, the girl's mother said no child should ever go through the trauma her daughter experienced.

"My tiny innocent girl was well aware of stranger danger, however this person was friendly to her and tricked her into following him," she said in a statement.

"No child should ever have to go through this type of trauma, and no sentence will ever be long enough to make up for the ongoing effects this will have on her."

Outside court, Free's lawyer Shaune Irving read a statement from Free who said he "can only ever say sorry".

"I know this is not good enough ... I can't take that back," the statement read.

"I do not wish to cause any further pain upon the young victim, her family nor delay justice any further.

"I took away her innocence and scared her family. I hope that today my sentence provides her and her family some closure."

Child safety campaigner Bruce Morcombe, father of murdered Sunshine Coast boy Daniel Morcombe, criticised Free's sentence as "skinny".

"I would suggest it's well below the public's standard of setting a sufficient deterrent for other creeps that are out there," Mr Morcombe told media.

Australian Associated Press