As a promising cathode material in sodium-ion batteries (SIBs) for large-scale energy storage applications, tunnel-structured Na0.44MnO2 is prepared by a facile and controllable urea-based solution combustion synthesis (SCS) method with subsequent calcination. The phase purity, morphology, homogeneity and particle size of the samples are quite dependent on the SCS fuel condition. The optimal sample f0.75 displays pure phase composition, high crystallinity and hierarchical-structured particles with uniform size of several microns, which are the agglomerates of well-calcined nano-rods and nano-slabs. The sample exhibits the highest reversible capacity of around 117 mAh/g at 0.1 C, good rate capability and excellent cycling stability, which even presents a high capacity of 100 mAh/g at 4 C after 300 cycles. The facile and controllable production and the superior electrochemical performance of the Na0.44MnO2 makes it a promising cathode material for the development of practical SIBs.