Tamara Kinnish had last been seen at school, close to the city centre, on Tuesday, March 19 at around 10.30am.
Lancashire Police had issued a public appeal to help find the 16-year-old.
A police spokesman said: "The 16-year-old girl who was missing from her home in Lancaster has been found safe and well.
"She was located safe and well this morning (March 24).
"We thank the public for their support in helping find her."