Machine-to-machine　(M2M)　communications　have　attracted　great　attention　from　both　academia　and　industry.　In　this　paper,　with　recent　advances　in　wireless　network　virtualization　and　software-defined　networking　(SDN),　we　propose　a　novel　framework　for　M2M　communications　in　software-defined　cellular　networks　with　wireless　network　virtualization.　In　the　proposed　framework,　according　to　different　functions　and　quality-of-service　(QoS)　requirements　ofmachine-type　communication　devices,　a　hypervisor　enables　the　virtualization　of　the　physical　M2M　network,　which　is　abstracted　and　sliced　into　multiple　virtual　M2M　networks.　In　addition,　we　develop　a　decision-theoretic　approach　to　optimize　the　random　access　process　of　M2M　communications.　Furthermore,　we　develop　a　feedback　and　control　loop　to　dynamically　adjust　the　number　of　resource　blocks　that　are　used　in　the　random　access　phase　in　a　virtual　M2M　network　by　the　SDN　controller.　Extensive　simulation　results　with　different　system　parameters　are　presented　to　show　the　performance　of　the　proposed　scheme.