Herein, a facile one-step method is developed to in situ prepare crystalline anatase and rutile TiO 2 nanocrystals on Ti 3 C 2 T x by regulating the metastable Ti ions. The combination of TiO 2 nanocrystals and Ti 3 C 2 T x not only introduces extensive accessible sites for Na + storage, but also promotes the charge transport by efficiently relieving the collapse of Ti 3 C 2 T x . Compared with pristine Ti 3 C 2 T x , the optimized TiO 2 /Ti 3 C 2 T x hybrid electrode (anatase/rutile-TiO 2 /Ti 3 C 2 T x , A/R-TiO 2 /Ti 3 C 2 T x ) exhibits a desirable specific surface area (22.5 m 2 g -1 ), an ultralow charge transfer resistance (42.46 Ω) and excellent ion diffusion (4.01 × 10 -14 ). Remarkably, rich oxygen vacancies are produced on TiO 2 /Ti 3 C 2 T x which is beneficial to enhance the insertion/de-insertion of Na + during the charge/discharge process. As a result, the A/R-TiO 2 /Ti 3 C 2 T x delivers a high average capacity of 205.4 mA h g -1 at 100 mA g -1 and a desirable capacitance retention rate of 84.7% can be achieved after 600 cycles at 500 mA g -1 .