The histone demethylase JMJD2C, also known as KDM4C/GASC1, has activity against methylated H3K9 and H3K36 and is amplified and/or overexpressed in human cancers. By the generation of Jmjd2c knockout mice, we demonstrate that loss of Jmjd2c is compatible with cellular proliferation, embryonic stem cell (ESC) self-renewal and embryonic development. Moreover, we report that JMJD2C localizes to H3K4me3 positive transcription start sites in both primary cells and in the human carcinoma KYSE150 cell line, containing an amplification of the JMJD2C locus. Binding is dependent on the double Tudor domain of JMJD2C, which recognizes H3K4me3, but not H4K20me2/me3 in vitro, thus showing a different binding specificity than the double Tudor domains of JMJD2A and JMJD2B. Depletion of JMJD2C in KYSE150 cells has modest impact on H3K9me3 and H3K36me3 levels, but impairs proliferation and leads to deregulated expression of a subset of target genes involved in cell cycle progression. Taken together, we show that JMJD2C is targeted to H3K4me3 positive transcription start sites, where it can contribute to transcriptional regulation, and report that the putative oncogene, JMJD2C, is not generally required for cellular proliferation or embryonic development.