Police say a 48-year-old man with an extensive criminal history was ambushed and executed in the underground carpark of an apartment building about 8.15am on Tuesday in Spring Street, near the popular Westfield shopping centre.
The victim has not been formally identified but media reports named Alen Moradian, a notorious Sydney underworld drug lord with links to the Comanchero bikie gang.
Detective Superintendent Danny Doherty from State Crime Command's Homicide Squad says police are treating the shooting as an organised crime murder.
"This was a well planned and executed murder of a high-level criminal identity," he told reporters.
"He's a major player. He obviously had a target on his back."
Police believe at least two shooters were involved.
Nicknamed "Fathead", Moradian was arrested in 2007 along with his wife Natasha Youkhana and others over what police at the time called one of the largest cocaine and money laundering rackets in NSW history.
Moradian was sentenced to 16 years and nine months in jail for importing and supplying cocaine.
During his trial, the court was told Moradian and Youkhana lived a life of luxury, using drug money to buy property, designer furniture, jewellery, a wedding reception, luxury travel and accommodation.
An email showed Youkhana urging her husband to be more like "Tony Soprano", for fear their over-the-top lifestyle would result in them getting caught.
"Why do you just sit there and show off - 'I am the man, I am the man'?" the email, tendered in police facts, read.
"Do you see Tony Soprano doing that?
"He doesn't care who people think is the boss, (money) is his number one priority. You, on the other hand, want the attention, you get a big head, you love it.
"People like that won't survive."
Roads surrounding the scene of Tuesday's shooting were closed, with people told to stay away.
"This is Tuesday morning in Bondi Junction, we don't expect this to happen. We don't expect it to happen anyway," Det Sup Doherty said.
"Police are out there now, knocking on doors to make sure there's no retaliation or escalation."
Police belive a burnt-out Porsche found on James Street, Bondi Junction, about the same time is linked to the shooting.
Detectives are also investigating whether a second torched car - a Holden Commodore found on Cook Lane, Zetland - is linked to the shooting.
Three crime scenes have been established.