The woman's body is still in the alley covered by a blanket because the body can not be removed while the police operation is continuing.
According to The Daily Telegraph, a pedestrian found the body in an alley near Chatswood train station on Monday morning at about 6.30am.
The dead woman was thought to be aged in her 20s.
Two officers wearing helmets and harnesses were positioned in an area above him.
The man is now on the awning of a balcony on the 26th floor of the apartment block on Brown Street and the street has been cordoned off by police, with traffic diverted.
Temperatures in Sydney climbed to about 30C during the day and the man was given cigarettes and water.
A day-long stand-off between a man perched above a balcony in Sydney's Chatswood and police has finally come to an end, with the unnamed man taken into custody. Fairfax reports a Korean translator is assisting police.
About 40 minutes later, police saw a man lying on an awning above a 27th-floor balcony.
The macabre situation drew a crowd of spectators.
"As soon as I saw the man it was just gut-wrenching", Mr Pulakhandam told AAP.
Call Lifeline on 13 11 14 for 24-hour crisis support and suicide prevention.