The mouse delta‐like homolog 1 and type III iodothyronine deiodinase (Dlk1–Dio3) imprinted domain contains three known paternally methylated differentially methylated regions (DMRs): intergenic DMR (IG‐DMR), maternally expressed 3‐DMR (Gtl2‐DMR), and Dlk1‐DMR. Here, we report the first maternally methylated DMR, CpG island 2 (CGI‐2), is located approximately 800 bp downstream of miR‐1188. CGI‐2 is highly methylated in sperm and oocytes, de‐methylated in pre‐implantation embryos, and differentially re‐methylated during post‐implantation development. CGI‐2, similarly to Gtl2‐DMR and Dlk1‐DMR, acquires differential methylation prior to embryonic day 7.5 (E7.5). Both H3K4me3 and H3K9me3 histone modifications are enriched at CGI‐2. Furthermore, CCCTC‐binding factor (CTCF) binds to both alleles of CGI‐2 in vivo. These results contribute to the investigation of imprinting regulation in this domain.