Kallan Richardson, 18, admitted at Grimsby Magistrates’ Court a charge of grievous bodily harm.
Jersey-Lou Perry suffered “horrendous injuries” after a brick was thrown through the window of her father’s van in April this year, police said at the time.
The little girl was said to have suffered a broken nose, two lost teeth and numerous other injuries to her face.
Her father, Kyle Perry, said the incident happened after he stopped to remonstrate with a group of youths after a ball hit his vehicle in Rutland Street, Grimsby.
Richardson, who was 17 when the offence was committed, appeared in court yesterday wearing a blue T-shirt and grey tracksuit bottoms.
He spoke only to confirm his name, date of birth and his guilty plea.
No details of the offence were read out in court.
Richardson was released on bail and the case was adjourned until September 12 for pre-sentencing reports to be prepared.
District Judge Daniel Curtis told Richardson that all sentencing options were open.
“There’s still a real prospect that you will lose your liberty,” the judge told him.
“I think it’s only fair that you know that is at the forefront of my mind at this stage.”