A novel device-to-device (D2D) aided uplink transmission scheme exploiting non-orthogonal multiple access (termed as D2D-UNOMA) is proposed and investigated. In D2D-UNOMA, two similar gain near users (NUs) and a far user (FU) can transmit their information to the base station (BS) in two time slots. The NUs can directly communicate with the BS, whereas the FU requires assistance of one of the NUs to facilitate the communication. In addition, as part of D2D communications, one of the NUs can transmit to the other NU in the first phase, whereas the FU can transmit to a NU in the second phase. The performance of D2D-UNOMA is studied in terms of ergodic rate along with analytical formulation. Through numerical results, it is demonstrated that the proposed D2D-UNOMA can ameliorate the ergodic sum rate significantly compared to the conventional orthogonal multiple access.