The cyclist, a woman believed aged 30, was pronounced dead at the scene [in Dulwich].
Next of kin have been informed. A post-mortem examination will be scheduled in due course.
The 40-year-old driver of the HGV lorry, a white Mercedes, stopped at the scene.
He was subsequently arrested in connection with the collision and taken into custody at a south London police station.
More top news
Police investigating the murder of a grandfather from West Ham have arrested a second man on suspicion of murder.
Police are appealing for information after a woman was killed and three people injured after a crash in east London.
A restaurant where pets and their owners can share a meal together has opened just in time for Valentine's Day.