ChatGPT has increasingly become an important technological tool for content marketing by helping businesses create, modify, personalise, and distribute marketing content more efficiently. However, concerns about the quality, authenticity, credibility, and trustworthiness of AI-generated content continue to raise questions about its effectiveness among consumers. This study examined the impact of ChatGPT on content marketing effectiveness and consumer trust in Nigeria, with specific focus on quality of marketing content, consumer engagement, and consumer trust. A cross-sectional survey research design was adopted for the study. Data were collected from consumers who had encountered or interacted with ChatGPT-generated marketing content using a structured questionnaire titled ChatGPT, Content Marketing Effectiveness and Consumer Trust Questionnaire (CCMECTQ). The data collected were analysed using descriptive statistics and Multiple Linear Regression Analysis with the aid of SPSS Version 26 at the 0.05 level of significance. The findings revealed that ChatGPT has a significant positive influence on the quality of marketing content produced by businesses in Nigeria. The study also found that ChatGPT significantly affects consumer engagement with marketing content, while ChatGPT-generated marketing content has a significant positive influence on consumer trust. The study concludes that ChatGPT can contribute positively to content marketing by improving the quality of marketing content, encouraging consumer engagement, and strengthening consumer trust when appropriately applied. It recommends that businesses should use ChatGPT to develop relevant and engaging marketing content while maintaining human review to ensure accuracy, authenticity, and cultural relevance.