The colorful mythological bird symbolizes rebirth and rising from the ashes and Affleck may have been inspired to get the tattoo after his highly publicized split from wife Jennifer Garner, reported E! News.
The back tattoo is "not new", according to a source and it seems the actor gave a sneak peek of the inking in July.
Besides his recent gigantic body art, the actor has several other tattoos including a barbed wire across his right bicep, a large design featuring a fish and a skull and crossbones on his right arm, some initials inscribed on his shoulder blade, and a dolphin on his right hip covering up the name of his high-school sweetheart.
There were reports that Affleck allegedly cheated with his children's former nanny though the actor denied it.