The teenager was pronounced dead at the scene, following the crash in New Malden at about 08:30 GMT.
The lorry driver, who was not arrested, stopped following the collision in Lime Grove.
Det Sgt John Hartfree, of the Met Police, appealed for drivers and pedestrians who witnessed the crash to come forward.
A 13-year-old girl died when she was struck by a lorry while walking along a street in south-west London.