The demand for wireless access continues to grow with the new applications which create a broad range of technical challenges. Although orthogonal frequency division multiplexing (OFDM) with multiple numerologies concept will likely address the current technical challenges of fifth generation (5G) wireless networks, the sufficiency of OFDM-based physical layer (PHY) is quite disputable due to massive growth trend on the number of wireless users and applications for future wireless networks. Therefore, enhanced radio access technologies (RATs) are needed to fulfill the technical requirements of beyond 5G networks. Generalized frequency division multiplexing (GFDM) has attracted tremendous attention over the past few years because of its advantages in terms of out-of-band (OOB) emission, spectral efficiency and latency. Index modulation (IM) techniques convey digital information by utilizing transmission entities in an innovative way and offer attractive advantages such as energy and spectral efficiency without increasing the computational complexity. On the other hand, multiple-input multiple-output (MIMO) transmission is an unquestionable technology to enable increased spectral efficiency. In this paper, a novel MIMO-GFDM scheme, which combines spatial multiplexing (SMX) MIMO transmission, GFDM and IM, is proposed in order to provide an efficient transmission scheme for beyond 5G wireless networks. A minimum mean squared error (MMSE)-QR decomposition-based near-optimum detector is proposed for the receiver side and bit error rate, OOB emission, spectral efficiency and computational complexity of the proposed scheme are compared with classical SMX-OFDM and SMX-GFDM schemes via computer simulations. It has been demonstrated that the proposed SMX-GFDM-IM scheme can be considered as a viable PHY scheme for beyond 5G wireless networks. (C) 2019 Elsevier B.V. All rights reserved.