Apple said the event will occur at its Cupertino, California, headquarters, beginning 1pm ET (3am 11 September AEST), and included paste circles of green, blue, purple, red and yellow on the invitation.
Apple also included the tagline "this should brighten everyone’s day”.
The news comes as Samsung is widely expected to show its Galaxy Gear smartwatch tomorrow, which will sport "large" square OLED display, a 4-megapixel camera, 10 hours of battery life, and a customised version of Android.
Apple on the other hand is expected to break tradition and launch not one but two iPhones at the event, a new high-end phone but also a lower-cost plastic model that omes in a variety of colours.
Apple will be hoping to get some momentum from the event, as recent statistics have showed Android has gained almost 80% of the worldwide smartphone market.