Optus D3 is an Australian geostationary communications satellite, which is operated by Optus and provides communications services to Australasia. D3 was the third Optus-D satellite to be launched. It is a 2,401-kilogram (5,293 lb) satellite, which was constructed by Orbital Sciences Corporation based on the Star-2.4 satellite bus, with the same configuration as the earlier Optus D2 satellite.

It was launched, along with the Japanese JCSAT-12 satellite, by Arianespace. An Ariane 5ECA rocket was used for the launch, which occurred from ELA-3 at the Guiana Space Centre in Kourou, French Guiana. The launch took place at 22:09 GMT on 21 August 2009, at the start of a 60-minute launch window.

Optus D3 separated from its carrier rocket into a geosynchronous transfer orbit, from which it raised itself to geostationary orbit using an IHI -500-N apogee motor. It has a design life of fifteen years, and carries thirty two J band transponders (US IEEE Ku band).

Optus D3 will be visited by Mission Extension Vehicle-1, which will dock to Optus D3 and extend the mission of the satellite by 5-7 years.