The 15-year-old boy was rushed to hospital but died after being hit on Manor Drive, Upton at 9.45pm on Monday.
Photos from the scene show his yellow and black mountain bike strewn in the road. Blue roses have been placed by the closest tree to where he was knocked off.
Police said that a silver SUV was involved and have arrested a 22-year-old local man in connection with the collision.
A Merseyside Police spokesman said: “At around 9.45pm, emergency services were called to Manor Drive, Upton, following reports of a collision involving a car and a cyclist.
“The cyclist, a 15-year-old boy, was taken to hospital where he sadly died. The car, described as a silver SUV, failed to stop at the scene.
“Following enquiries, a 22-year-old man from Wirral was arrested on suspicion of causing death by dangerous driving and failing to stop after a road accident.
“He remains in custody for questioning.
“The victim’s family has been informed and are being supported by specially trained officers.”
Road closures remain in place in the area and an investigation is underway.
Anyone who witnessed the collision or captured anything on CCTV or dashcam is asked to contact (0151) 777 5747, or via @MerPolCC on Twitter or ‘Merseyside Police Contact Centre’ on Facebook, with ref 21000266987.