This research paper investigates the various types of complement clauses in Ìtsẹ̀kírì, a Yoruboid language spoken in the Niger Delta region of Nigeria. Drawing from Noonan’s approach to complement clauses (2007), this study investigates the varied expressions of complementation in Ìtsẹ̀kírì, particularly its usage in the context of reported speech, indirect speech and expression of thoughts and feelings. The research primarily relies on data collected from native speakers of the language who exhibit a high level of fluency and proficiency in Ìtsẹ̀kírì. Additionally, relevant texts and academic journals on complementation were consulted. The objective of this paper is to identify the types and underlying grammatical structures of complement clauses in Itsekiri. Ultimately, this study seeks to deepens the understanding of complementation phenomena in Itsekiri and make significant contribution to the existing body of knowledge in terms of the syntactic analysis of Ìtsẹ̀kírì language, as well as to the broader field of linguistics.