Heptathlon champion Ennis, shotput champion Adams and 200 metres champion Felix received the most votes from a 2,400-strong panel.
Jamaica's Usain Bolt, American Aries Merritt and Kenyan David Rudisha are the three male finalists.
But Mo Farah was omitted from the shortlist to win the 2012 IAAF male athlete of the year.
The Somalia-born Briton completed a magnificent long-distance double of 5,000 and 10,000m at the London Olympics but the world governing body decided his achievement did not warrant inclusion.
Jamaican sprint king Usain Bolt, who retained his Olympic 100m, 200m and 4x100m relay titles, is considered favourite again for an award he won in 2008 and 2009.
Also shortlisted are David Rudisha and Aries Merritt.
Kenyan Rudisha set a world record in winning the Olympic 800m title while American Merritt won the 110m hurdles title then set a WR in the Brussels Diamond League event in September, taking seven-hundredths of a second off Dayron Robles's previous mark.
The winner will be announced in Barcelona on November 24.