SYDNEY'S population has passed the 4.5 million mark for the first time, with the inner-west area of Canada Bay the fastest-growing area, figures show.

The population of Sydney, still Australia's largest city, increased by 85,400 in the year to June 30 last year, according to figures from the Australian Bureau of Statistics.

Every local government area in Sydney recorded a population increase during that period. Blacktown, Parramatta and the Hills Shire had the largest increases in residents for the second consecutive year.

The population of Blacktown swelled by almost 7000 people in the year.