Emergency services were called to the intersection of Harry Ave and Maud St in Lidcombe around 4.45pm to reports a cyclist had been hit.
Despite the best efforts from paramedics, the man was unable to be saved and died at the scene.
Officers are working to identify the man and notify his family about the tragic incident.
NSW Police have established a crime scene around the man and are now searching for a woman who they say can give them information about the crash.
— Nine News Sydney (@9NewsSyd) May 7, 2019
In a statement, police said a vehicle had failed to stop after the incident and officers are appealing for assistance to locate the driver.
Witnesses described the car as being a white or grey sedan and said the driver was a woman of Asian appearance believed to be in her 30s.
Anyone with information is urged to contact police.