The present disclosure provides a wide-angle lens assembly and an imaging device equipped with the wide-angle lens assembly. The wide-angle lens assembly includes, sequentially from an object side to an image side: a first lens having a negative refractive power, where an image-side surface of the first lens is a concave surface; a second lens having a positive refractive power, where an object-side surface of the second lens is a convex surface; a third lens having a refractive power; and a fourth lens having a positive refractive power, where an image-side surface of the fourth lens is a convex surface. A sagittal height SAG12 of the image-side surface of the first lens at a maximum effective radius and the air spacing T12 on the axis between the first lens and the second lens satisfy: 1.5≤SAG12/T12