The 15-year-old was hit just before 3pm on Saturday, and suffered serious injuries. However, she was pronounced dead shortly after arriving at hospital.
West Midlands Police say the bus driver is helping officers as they establish what happened on Sheaf Lane in the Sheldon area of Birmingham.
PC Gail Arnold, from our serious collision investigation unit, said: "A young girl has tragically died and we'll be doing all we can to support her family during this deeply distressing time.
"We're working to establish the circumstances behind the collision and we're keen to hear from anyone who was in the area at the time, and especially anyone with dash cam footage."
Anyone with information can email officers at SCIU@westmidlands.police.uk or by contacting the force through Live Chat on its website, quoting log 2467 of 18 March.