The cephalopod visual system is a stunning example of convergence in a complex trait. However, little is known about the genetic and molecular basis of cephalopod eye development. A major contributor to the evolution of biological novelty is thought to be the duplication of genomic DNA. We sought to investigate if this might contribute to cephalopod-specific visual system novelties. Members of the Krüppel-like factor/specificity protein (KLF/SP) sub-family of C2H2 zinc-finger transcription factors were found to be highly expressed in the visual system transcriptome of the squid Doryteuthis pealeii. With few exceptions, the evolution and function of this gene family has not been studied in Spiralia. A thorough phylogenetic analysis found multiple duplications and losses of the SP6-9 gene throughout spiralian lineages and at least one cephalopod-specific duplication. We show in particular that D. pealeii expresses two recent duplicates of SP6-9 (a and b) in overlapping neural and limb domains but one paralog showed unique expression in the developing squid lens, suggesting a neofunctionalization of DpSP6-9a. We sought to further investigate the role of SP6-9a in the developing squid lens and found that DpSP6-9a is expressed in the lens in conjunction with a regulatory cassette typically found in proximal-distal patterning of animal appendages. This work supports the hypothesis that gene duplication and co-option contribute to the appearance of novel traits like the cephalopod image-forming eye and to the morphological diversity found within Spiralia.