Rankine is the sixth AFL-listed player suspended for a homophobic slur against an opponent in the past 16 months.
The star Crow will only play again this season if ladder-leading Adelaide lose a qualifying final en route to the grand final.
Adelaide play North Melbourne on Saturday in the last home-and-away round and will then host two finals.
Rankine admitted directing a homophobic slur to an unnamed Collingwood opponent in Adelaide's three-point win last Saturday night
"Izak has said he knew it was not acceptable," the AFL's general counsel Stephen Meade said in a statement announcing the four-game ban.
"Adelaide have said they know it is not acceptable.
"In an AFL environment, this behaviour is not acceptable. Homophobia has no place in football.
"The suspension is significant but stamping out vilification in our game is incredibly important."
Rankine, 25, apologised to the Magpie player on Sunday as the AFL's integrity unit launched an investigation.
Rankine is the sixth AFL-listed player banned for an on-field homophobic slur since April last year.
Last month, West Coast's Jack Graham was banned four games for a homophobic remark to a GWS player.
In April last year, Port Adelaide's Jeremy Finlayson was suspended for three games and, the following month, Gold Coast's Wil Powell was suspended five matches, both for directing homophobic slurs at opponents.
Two VFL players have also been banned for the same offence.
Sydney defender Riak Andrew last month was suspended for five matches for an anti-gay slur while playing in a reserves game against North Melbourne.
And in July last year, St Kilda's Lance Collard was banned six games for homophobic comments while playing in the VFL for Sandringham against Williamstown.
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