One-dimensional multi-walled carbon nanotubes (MWNTs) have unique electrical properties, but they are not solution-processable, which severely limits their applications in microelectronic devices. Therefore, it is of great significance to improve the solubility of MWNTs and endow them with new functions by chemical modification. In this work, MWNTs were in situ functionalized with poly[(1,4-diethynyl-benzene)-alt-(3-hexylthiophene)] (PDHT) via Sonogashira-Hagihara polymerization. The obtained material PDHT-g-MWNTs was soluble in conventional organic solvents. By sandwiching a PDHT-g-MWNTs film between Al and ITO electrodes, the fabricated Al/PDHT-g-MWNTs/ITO electronic device exhibited nonvolatile rewritable memory behavior, with highly symmetrical turn-on/off voltages, a retention time of over 104 s, and durability for 200 switching cycles. These findings provide important insights into the development of carbon nanotube-based materials for information storage.