The ERK5 MAP kinase signalling pathway controls key processes in mouse Embryonic Stem Cells (mESCs) maintenance, including expression of naïve pluripotency genes and a transcriptional programme for stem cell rejuvenation. However, quantitative proteomics suggests that ERK5 signalling controls levels of proteins implicated in diverse biological processes. Here, we show that Annexin A2 (ANXA2) and its accessory protein S100A10, which are implicated in regulation of membrane dynamics, are major targets of the ERK5 signalling pathway in mESCs. ERK5 activation promotes expression of the ANXA2/S100A10 protein complex via transcriptional induction of the KLF2 pluripotency factor. Furthermore, either ERK5 signalling or ectopic expression of the ANXA2/S100A10 complex promotes formation of membrane protrusions in mESCs. Our data therefore identify a new function for the ERK5 pathway in regulation of an Annexin complex and membrane dynamics, which may have implications for development and disease.