An optical imaging lens assembly includes five lens elements which are, in order from an object side to an image side: a first lens element, a second lens element, a third lens element, a fourth lens element and a fifth lens element. Each of the five lens elements has an object-side surface facing toward the object side and an image-side surface facing toward the image side. The first lens element has positive refractive power. The object-side surface of the first lens element is convex in a paraxial region thereof. The second lens element has negative refractive power. The object-side surface of the fourth lens element is convex in a paraxial region thereof. The fifth lens element has negative refractive power. The image-side surface of the fifth lens element is concave in a paraxial region thereof and has at least one convex critical point in an off-axis region thereof.