Rebecca O'Brien has been located safe and well.
Gardaí have thanked the public for their assistance.
Rebecca O'Brien has been missing from the Dublin 1 area since September 16.
She is described as being 5'10", with brown hair.
She has an average build and blue eyes.
When last seen Rebecca was wearing a black top, black shoes, blue jeans and carrying a yellow bag.
Anyone with information on her whereabouts are asked to contact Gardai in Mountjoy on 01 666 8600 or the Garda Confidential Line on 1800 666 111.