A 18-year-old who beat down another teenager inside a Brooklyn McDonald’s was sentenced Friday to four years in prison.

Aniah Ferguson, who was 16 years old at the time of the assault, was handed the sentence from Brooklyn Supreme Court Justice Dineen Riviezzo when she arrived late to the court room after a refusing to leave her cell.

“Apparently, she’s not cooperating with the officers,” a court officer told The Post.

“She’s probably a little anxious. I’m pretty sure she’s not expecting good news.”

The teen mom and admitted Crips member was convicted of the 2015 attack on 16-year-old Ariana Taylor inside a Flatbush Avenue McDonald’s in April after a video of the brutal beat down went viral in the internet.

She was first sent for psychiatric treatment at facility for adolescents, but was remanded to Rikers Island in November due to her unruly behavior.

“The court has now given Miss Ferguson… every opportunity, over and over and over again to demonstrate that she can be a law-abiding, productive member of society,” Judge Riviezza said about the teenager’s treatment.

“Her conduct just became worse.”

Ferguson suffers from mood and conduct disorders, sources have said.