The title compound, [Na(C2BF2O4)(CH3CN)2]n, forms infinite two-dimensional layers running parallel to (010). The layers lie across crystallographic mirror planes at y = 1/4 and 3/4. The Na, B and two F atoms reside on these mirror planes. The Na+ cations are six-coordinate. Two equatorial coordination positions are occupied by acetonitrile molecules. The other two equatorial coordination sites are occupied by the chelating O atoms from the difluoro(oxalato)borate anion (DFOB−). The axial coordination sites are occupied by two F atoms from two different DFOB− anions.