This article examines the evolving, dual role of Nigerian legal practitioners within the anti-money laundering (AML) and counter-terrorism financing (CFT) framework. It traces the historical emergence of money laundering in Nigeria. It analyses the progressive development of legal and regulatory responses, highlighting the profession’s initial resistance to being designated as a Designated Non-Financial Business or Profession (DNFBPs). This resistance, rooted in the sanctity of attorney-client privilege, created a regulatory gap that was often exploited for illicit financial flows. The article critically assesses the pivotal shift introduced by Chapter Two of the 2023 Rules of Professional Conduct (RPC) for legal practitioners. This new chapter represents the legal profession’s formal, self-regulatory acknowledgement of its responsibility in combating financial crimes. It imposes specific obligations on lawyers, including client due diligence (CDD), record-keeping, risk assessment, and the mandatory reporting of suspicious transactions to the Nigerian Bar Association Anti-Money Laundering Committee (NBAAMLC). This research adopts a doctrinal research method. The RPC 2023, particularly Chapter Two, imposes significant Anti-Money Laundering and Combating the Financing of Terrorism (AML/CTF) obligations on legal practitioners, effectively casting them in a "dual role" as both zealous advocates for their clients and essential gatekeepers for the financial system. This dual mandate creates an inherent tension, particularly concerning the sacred duty of client confidentiality and the mandatory reporting of suspicious transactions. Finally, the article identifies key challenges to the effective implementation of this new ethical regime, including potential resistance from practitioners, weak enforcement mechanisms, and inadequate awareness. It concludes that for Nigeria’s AML/CFT efforts to be robust, lawyers must embrace their dual role not merely as client advocates but as essential gatekeepers of the financial system’s integrity. The successful implementation of Chapter Two’s provisions will be crucial to reshaping professional ethics and bolstering Nigeria's fight against money laundering and terrorism financing.