The aim of the present article is to leverage new materialism as a framework for re-conceptualising teachers' digital professional development. Building upon the Deleuzo-Guattarian concepts of affect and machinism, I suggest that technology use cannot be conceptualised as pre-given property or service of independently existing entities. Instead, it needs to be studied as a relational phenomenon in its ongoing materialisation. I further argue that technologically supported processes of teachers' professional development cannot have a pre-existing status, since they gain substance only when drawn into machinic encounters occurring between human and non-human entities. My main argument is that such encounters generate new potential that interrupts and differentiates the intensity and quality of teachers' becoming-with-technology. By building upon these insights, I propose the concept of "techno-ontology" as an ontology of meaning that can help teacher educators re-examine the multiplicity of the affective forces that constitute the conditions of human-technology interaction. This is a vision that seeks to free teachers' professional development from rigidified standards of digital competence and attend to its reinvestment as a creative process of digitally agentic becomings.