Goddard, 27, told the Essendon website he was excited to be joining the Bombers on a four year deal after exploring his options as a restricted free agent.
“I would like to thank James Hird and the Essendon Football Club for the opportunity they have presented me, and I look forward to committing everything I have to them just as I have done for St Kilda over the past 10 years,” Goddard said.
“Career decisions are always difficult and this has certainly been the case for me.
“I’d like to thank the St Kilda Football Club for everything, especially my teammates, many of who will always be close friends away from the football field. I appreciate that many St Kilda supporters will be disappointed with my decision but I hope they respect it.”
Goddard is currently overseas on annual leave and will join his new teammates at a training camp in Colorado in early November.