Thomas Dunn, 25, claimed he had only “assisted” the toddler after he seen her climbing into the machine herself.
Dunn, of Hamilton, Lanarkshire, said he did not fully close the machine door on the child but the dryer had activated and started rotating.
The attack caused the child, who cannot be named for legal reasons, to sustain skull fractures. On another occasion, he struck the child on the head and body causing her severe injury.
Dunn was found guilty of a charge of culpable and reckless conduct and a charge of assault in June 2019 after a trial at Dundee Sheriff Court.
Sheriff Alistair Brown told Dunn that he could only impose a five year sentence on him. Sheriff Brown said he didn’t think that sentence would be sufficient and sent him to the High Court to be sentenced.
On Monday, judge Lord Brodie sentenced Dunn to seven years in prison. He also ordered him to be supervised by the authorities for three years following his release from custody.
Passing sentence, Lord Brodie said: “You have been found guilty after trial of very serious offences against a one-year-old child who had been in your care.
“As you yourself accept, there is only sentence I can impose for these offences and that is custody.
“You will go to prison for seven years and you will be supervised for a further three years.”
During proceedings earlier this year, the court heard how the attacks took place at an address in Arbroath over a two week period from December 18 2017 to January 8 2018.
Dunn, originally of Brechin, was convicted after claiming in evidence that he tried to help the little girl climb into the washing machine.
He said he was “mucking around”.
On January 8, he assaulted the same girl by striking her on the head and body, striking her against an “object” and biting her.
He claimed he had found the child lying limp while he was caring for at a house in Arbroath.
She was taken to hospital and medics found she had sustained brain injuries.
Doctors contacted police who found enough evidence to prove Dunn was responsible for her injuries.
Sheriff Brown told Dunn that there was no other option but to send him to the high court.
He added: “You must have hit that little girl extremely hard at least twice in order to inflict potentially catastrophic damage to her.
“It’s only by good fortune that you were not in the high court on a charge of murder.
“The assault charge is so monstrous and carried out with such utter indifference to this little girl’s life that my powers are not adequate to deal with you.
“I interpret the verdict at best that you assisted her into the tumble dryer and closed the door whereas what you ought to have been doing as a responsible adult was stopping her from getting in in the first place.”
On Monday, defence advocate Niall McCluskey told the court that his client had suffered from mental health problems.
He added: “He suffers from depression and mental health problems. He also accepts that the imposition of a prison sentence is inevitable.”
Lord Brodie then ordered him to be taken into custody.