To improve electrochemical performance of MnO electrodes, the porous 3D interconnected MnO/C composite aerogel is, at first, fabricated through direct carbonization of polyacrylic acid (PAA)-assisted manganese-based aerogel. Herein, the influences of carbonization temperature and the amount of PAA on the microstructure and lithium storage performance of composites are presented. MnO/C composite aerogel n3-550 (carbothermal reduction at 550 °C with the 30 mmol addition of PAA) shows the minimal MnO crystalline size, and the MnO/C composite aerogel n3-650 (carbothermal reduction at 650 °C with the 30 mmol addition of PAA) has the largest surface area and highest porosity. When evaluated as anodes for lithium ion batteries, the composite n3-550 exhibits the highest reversible capacity of 1081.8 mAh g−1 after 100 cycles at current density of 0.2 A g−1, n3-650 electrode displays the most outstanding rate capability (601 mAh g−1 at 2 A g−1), and the highest coulombic efficiency (initial coulombic efficiency of 69.8% and greater than 98% after the 6th cycles). These excellent electrochemical performances are as a result of the porous interconnected 3D networks composited of hybridized nano-MnO with carbon, providing outstanding electrical conductivity and 3D charge transport channels. This facile and efficient strategy provides a horizon and deep understanding for advancing the design of high-performance oxide based anode materials.