Research shows a positive association between skilled migration and innovation. Related literature however is largely limited to the use of proxies such as patents, and publications. There is also a lack of attention to how innovation is accomplished in practices. This paper addresses these gaps with an examination of the innovative contributions made by immigrant engineers in Canada. Conceptually, informed by practice-based theories, it conceives innovation as a sociocultural and sociomaterial process that leads to the transformation of the object/motives of activities, i.e. the problem space to which actions are directed. Empirically, drawing on a thematic and situational analysis of the career accounts of 32 immigrant engineers, it shows that immigrants expand engineering practices by introducing, inter alias, new technologies, products, processes, policies and standards. It further traces the rise of the problem spaces, and the ways in which engineering objects and other practitioners are knotted into practices of innovation. It argues that while immigrants manage to introduce epistemic objects through continuous learning and knowledge translation, it is through the enrolment of other practitioners, and technologies and tools that relations of differences and power are (re)negotiated, and new ways of doing become amplified as innovation at work.