A modified conjugated diene-based polymer and a rubber composition including the same are disclosed herein. The modified conjugated diene-based polymer has excellent processability and good tensile strength and viscoelasticity. In some embodiments, a modified conjugated diene-based polymer includes a derived unit from a modifier, the modifier including three or more alkoxy groups bonded to silicon; a non-functional chain forming a silicon-carbon bond at one side of the derived unit from a modifier and including a repeating unit derived from a conjugated diene-based monomer; and a functional chain forming a silicon-carbon bond at the other side of the derived unit from a modifier and including two or more derived units from an N-functional group-containing monomer.