Climate transition plans are emerging as new ways of involving businesses in climate action. Without their engagement, the transition towards climate neutrality will be challenging. Voluntary undertakings by individual companies, and various initiatives on best practices and standards currently dominate. The EU has decided to require the largest companies operating in the internal market to develop and implement a climate transition plan with legal consequences. The idea is to compel companies to ensure that their business models and practices align with the transition to a sustainable economy, the global temperature goals of the Paris Agreement, and targets of the European Climate Law. This paper undertakes an in-depth analysis of Article 15 of the draft EU Directive on Corporate Sustainability Due Diligence that introduces a climate transition plan as a legal instrument to combat climate change. Considering the directive’s pending approval, the paper will assess the legal nature, function, content elements and enforceability of the plan, as well as its relationship with the mandatory corporate sustainability due diligence outlined in the EU institution’s proposals.