External experts play a crucial role in implementing the UN Guiding Principles on Business and Human Rights, advising businesses on how to identify, prevent and mitigate risks. Yet their responsibility remains underexplored in relation to judicial remedy. This article addresses this gap by investigating the involvement of external experts in strategic litigation concerning alleged corporate human rights harms. While such litigation primarily seeks remediation and societal change, it also reveals overlooked actors within legal processes. Using the concept of ‘visibilisation’, this study examines three landmark cases to explore how courts understand experts’ legal subjectivity. Findings suggest that this subjectivity encompasses both an evidentiary and functional role in corporate processes, raising important questions regarding accountability. By highlighting their influence on the corporate responsibility to respect human rights and human rights due diligence (HRDD), the article advances understanding of expert responsibility and considers its future in the emerging era of mandatory HRDD.