17-year-old Jasmir Womack was sentenced Thursday to 6 to 23 months in prison.
She pleaded guilty to charges of conspiracy to commit aggravated assault and conspiracy to recklessly endanger another person.
Investigators allege that six female defendants - apparently for fun - punched, kicked and hit the 48-year-old woman with a shoe and a chair in Chester in September.
One recorded the beating and the video was posted online.
On Tuesday, 16-year-old Rahmiyah Henderson was sentenced to six to 23 months in Delaware County prison after she, too, pleaded guilty to conspiracy to commit aggravated assault.
Both girls also received two years consecutive probation on the misdemeanor charge of recklessly endangering another person.
Each will also attend anger management classes.
Henderson and Womack and the four other girls were all charged as adults in the case, which made national headlines.
Takia Nicole Edwards, 19 is scheduled for a Feb. 26 court appearance.
Jamia Davis, 15, Janyea Bell, 16, and Anye Dennis, 16, have hearings scheduled for March 11.
The Associated Press contributed to this report.