Megan Holland was last seen in Preston at around 6pm on March 16.
Police said they were growing concerned for the 17-year-old’s welfare and launched a renewed appeal to find her on March 23.
In an update posted later the same day, officers confirmed Megan had been found safe and well.
“Earlier today we asked for your help in finding missing 17-year-old Megan,” a spokesman for Lancashire Police said.
“Just to update you, Megan was found safe and well this afternoon.
“Thanks to everybody who shared our appeal.”