It is understood the 25-year-old Hawk will become an Eagle within days as his management and the club work out the final details of a contract.
Find out who's coming and going in the Gillette Trade Hub
As an unrestricted free agent, Ellis will be free to join the Eagles without the Hawks matching their offer.
West Coast football manager Craig Vozzo said the move to make Ellis an Eagle was close to being over the line.
"We're not quite there but we're really confident we'll finalise all of those details and terms tomorrow (Wednesday) to make that happen," Vozzo told 6PR on Tuesday night.
Vozzo said he also expected things to "heat up" with Brisbane Lion Elliot Yeo, who wants to leave Queensland and become an Eagle.
He said the club was committed to Yeo who remained a priority.
But Vozzo was less hopeful of the Eagles acquiring contracted Carlton defender Josh Bootsma.
Ellis had been undergoing fitness tests at Fremantle and West Coast but it is believed the Dockers have decided not to pursue the 2008 premiership player.
The wingman has endured many injury issues since the Hawks recruited him in 2005 and has played just 16 senior games in three years.
Last year, he suffered foot, calf and knee problems and didn't play in the AFL until round 20.
The left-footer played in the Grand Final loss to the Sydney Swans but was subbed off with a calf injury in the third quarter.
This year, he again endured problems with his calf and played just two senior games in rounds 13 and 14.
Ellis may have the chance to continue his career underneath new Eagles' coach Adam Simpson, who he has a relationship with from their days at the Hawks.
He was drafted with the third selection overall in the 2005 NAB AFL Draft as a priority selection behind Marc Murphy and Dale Thomas.
Other players who have changed clubs through free agency this month are Colin Sylvia (Melbourne to Fremantle), Matt White (Richmond to Port Adelaide), Eddie Betts (Carlton to Adelaide), Lance Franklin (Hawthorn to the Sydney Swans) and Dale Thomas (Collingwood to Carlton).
Twitter: @AFL_JenPhelan
