Quiros notched his fourth European Tour with the overtime triumph at the Real Club de Golf in Seville, Spain.
After he and Quiros finished regulation tied at 11-under 277, Morrison pulled his approach shot on the par-4 18th hole into the water to the left of the green. Quiros' approach shot landed only 12 feet from the pin.
After taking his drop, Morrison put his third shot 25 feet past the cup, and his miss of a bogey putt gave the win to the Spanish favorite.
Morrison's loss spoiled his bid to join Charl Schwartzel as the only multiple winner on the European Tour so far this year.
Third-round leader Mark Foster almost made it three-way playoff but missed a 3-foot par save on the 18th hole, falling to third place, which he shared with Alejandro Canizares and Raphael Jacquelin at 10-under 278.