The present article explores the impact of international humanitarian law (IHL) on the consolidation and development of the principle of systemic integration. The analysis relies on the jurisprudence of those international judicial and quasi-judicial bodies that have used IHL for interpretive guidance when applying human rights law in armed conflict. Whereas much attention has been paid to the substantive outcome of the interplay between these two bodies of law, too little consideration has been devoted to the role of systemic integration within this context. Human rights bodies and the International Court of Justice resort to this principle in three ways, namely by means of Article 31(3)(c) of the Vienna Convention on the Law of Treaties (VCLT), through equivalent provisions included in certain human rights treaties, or implicitly. In that regard, systemic integration is employed either to reinforce the application of human rights law by way of IHL, or to avoid norm conflict between diverging norms, especially in relation to the use of force and detention. The article identifies the kinds of impact that IHL has or may have with regard to the consolidation of the principle of systemic integration within the interpretive principles codified in the VCLT and in terms of the modification of some of its constitutive elements. It also aims to demonstrate that systemic integration, rather than lex specialis, is the principle of interpretation most pertinent to the interaction between IHL and human rights law.