In recent years, lead-free energy storage ceramics have been widely used as a new type of energy storage material with great application prospects. In this study, a modified NaNbO3 (NN) based ceramic, Na0.7Bi0.1NbO3 (NBN), is used as the matrix, and Ba0.9Sr0.1TiO3 (BST) is added as a doping agent. A series of (1-x)Na0.7Bi0.1NbO3-xBa0.9Sr0.1TiO3 (xBST, x = 0.1, 0.2, 0.3, 0.4) solid solutions have been designed and prepared using the solid-phase sintering method. The breakdown field strength (Eb) of 0.3BST ceramics reached 445 kV/cm, an unexpectedly ultra-high energy storage density (W) of 4.48 J/cm3 and a recoverable energy density (Wrec) of 3.47 J/cm3. In terms of charging and discharging performance, the ceramics have a low charging and discharging time of t0.9 = 1.38 μs. In addition, 0.1BST exhibits a high energy conversion efficiency of η = 87.35 %. These results confirm that (1-x)NBN-xBST ceramics are promising energy storage materials.