This paper examines the relationship between mantram, posture and siddhi (attainment, virtuosity) in kaḷarippayaṟṟ˘, the martial and medical system from the Malabar region of Kerala in Southwest India. While rooted in Malayali culture and society, kaḷarippayaṟṟ˘ shares with yoga its emphasis on guru–śiṣyan transmission, the refinement of the material body as a tool to harness and activate a subtle inner counterpart, and the use of mantram, both in the process of initiation into higher knowledge and as a specific link to kaḷari posture (vaṭiv˘ in Malayalam). This paper lays out the relationship between mantram and vaṭiv˘ in kaḷarippayaṟṟ˘ and the understanding of siddhi in this context. I do so through an examination of texts in Malayalam of the CVN lineage and their use in its lived practice, addressing how issues of authority in mantram transmission adapt to an evolving lived experience. Building on fieldwork from my doctoral research with more recent ethnography through the ERC-Synergy MANTRAMS Project, this paper draws on a relationship since 2002 with CVN Kalari Sangham at East Fort in Thiruvananthapuram to consider how the association between mantram and posture in kaḷari lineages expands and complicates our understanding of mantra in yoga.