"New allegations of sexual harassment as well as gender and racial discrimination among the rank and file have recently been brought to my attention," Mayor Jim Kenney said in a statement. "While those allegations do not accuse Commissioner Ross of harassment, I do ultimately believe his resignation is in the best interest of the Department."
Kenney cited new sexual harassment prevention policies and internal reforms within the department that he felt Ross did not proactively help to implement.
"While rolling out a new policy understandably takes time, I do not believe the Police Department has taken the necessary actions to address the underlying cultural issues that too often negatively impact women — especially women of color," Kenney said.
The Philadelphia Police Department (PPD) did not immediately comment.
Ross, who has been commissioner since January 2016 and has served in a number of departments including patrol, special operations, the detective bureau, homicide and internal affairs for nearly 30 years, will be replaced in the interim by PPD Deputy Commissioner Christine Coulter.
"I believe new leadership will help us continue to reform the Department and show that racial, ethnic, and gender discrimination simply will not be tolerated," Kenney said.
Kenney also said that he is "disappointed" by Ross' resignation "because he's been a terrific asset to the Police Department and the City as a whole," but believed the move was "in the best interest of the Department."
Ross' departure came nearly a week after an hourslong shootout between police and an armed gunman that resulted in six officers being shot.
Kenney heralded Ross as the best commissioner in America after officers from the PPD as well as several other law enforcement agencies were able to successfully negotiate the alleged shooter's peaceful surrender.
Fox News' Griff Jenkins contributed to this report.