At present, alcohols are considered sustainable starting materials that can be used in organic synthesis for various organic transformations and the preparation of commodity chemicals. Acceptorless dehydrogenation (AD) and borrowing hydrogen (BH) are two important methods for activating alcohols for alkenylation and alkylation. These approaches are sustainable because their process liberates water and in some cases (i.e., AD) molecular hydrogen as clean byproducts. Moreover, this area of research has attracted significant attention in the catalysis community, and various transition metals have been used to explore the same. Herein, in this review, we focus on the development of Ru-based catalyst systems for C-alkylation/alkenylation reactions via the AD or BH approach. This review also features a comparative study of the various Ru-catalysts used to optimize the reaction conditions. Furthermore, we extensively cover the outcomes of the mechanistic studies to describe the reaction pathways.