Background: In the existing literature, there are many guidelines regarding cultural competencies for healthcare professionals and many instruments aiming to measure cultural competence. However, there is no consensus on which core cultural competencies are necessary for healthcare professionals. Aim and Methods: This study employed the PRISMA 2020 statement to systematically review Delphi studies and identify the core cultural competencies on which experts, who have been working with diverse populations in the fields of healthcare and allied healthcare, have reached a consensus. For this purpose, we searched, retrieved, and reviewed all Delphi studies conducted between 2000 and 2022 in the databases Scopus, PubMed, CINAHL, Medline, and PsycInfo and coded and synthesised the results qualitatively. Results: The systematic search resulted in 15 Delphi studies that met eligibility criteria and in which 443 experts from 37 different countries around the globe had participated. The review of these Delphi studies showed that the core competencies necessary for healthcare professionals to ensure that they provide culturally congruent care were: Reflect, Educate, Show Interest and Praise, Empathise, and Collaborate for Therapy. Discussion and Conclusion: These competencies make the abbreviation and word RESPECT, which symbolically places emphasis on respect as the overarching behaviour for working effectively with diversity. The study also provides a new, comprehensive definition of the cultural competence of healthcare professionals and opens new directions in formulating standardised guidelines and research in cultural competence in healthcare and allied healthcare.