<p>This commentary discusses the exponential growth in the use of general purpose, generative artificial intelligence (GenAI) chatbots for mental health support. While mental health apps have historically struggled with user adoption and retention, GenAI chatbots are experiencing unprecedented levels of uptake that warrant examination via an implementation lens. Our commentary is informed by Diffusion of Innovations, a classic implementation science theory which posits that five key features influence the adoption of a new technology: its relative advantage, complexity, trialability, compatibility, and observability. The authors conducted a review of the recent literature via Google Scholar searches as well as by reviewing the reference lists of relevant publications. Additional sources were obtained via Google searches. We argue that general purpose GenAI chatbots have achieved high rates of adoption in part because they demonstrate a relative advantage over alternatives, are easy to use and trial, are compatible with the values and behaviors of certain populations, and are highly visible on a global scale. While early studies have reported positive views of GenAI chatbots as sources of mental health support, these tools lack strong guardrails and may not be providing evidence-based or effective guidance. However, severe mental health care shortages worldwide will lead many to choose between support from a chatbot or no support at all. Thus, it will be critical to continue monitoring the use of these tools and to work towards developing safe, high-quality options that can achieve both strong levels of engagement and clinical effectiveness.</p>