It includes three offensive selections and two on the defensive side of the ball.
Additionally, wide receiver Trey Metoyer was chosen as the Big 12 Newcomer of the Year.
Habern is the only repeat selection for the OU offense after earning the honor last year, while Ikard is the lone first team All-Big 12 member from a previous season, doing so in 2011.
Stills finished the 2011 campaign with 61 catches for 849 yards and eight touchdowns, and that was good enough to place him on second team.
Jefferson is the only other player out of the five to have gained a Big 12 end-of-season mention, as he earned honorable mention last season after leading the team with four interceptions to go along with 74 tackles.
McFarland managed 20 tackles, including 3.5 for loss, while playing in 13 games last year and starting 11 of those.
Metoyer, who went to Hargrave Prep School last fall and did not arrive on campus until last spring, led all OU receivers in the Red-White game with 72 yards on six receptions.
The six will start trying to live up to their preseason hype when fall camp begins Aug. 4.
Before that, though, the media Preseason Big 12 Poll will be released Thursday and Big 12 Media Days will convene July 23-24 in Dallas.