We developed the A.I. Math Personalization Tool (AMPT) to enhance cultural relevance in math word problems by giving students agency over the content. AMPT leverages generative AI to directly engage students as co-authors of math word problems. Through scaffolded conversations, the AI allows students to provide the context for a problem. Then, the AI integrates that context with the pedagogical standards of a target learning domain. We measured the attitudes of students towards mathematics before and after interaction with AMPT. After a single 30-min session co-authoring math word problems with AMPT, students’ sense of belonging in mathematics significantly increased, while other attitudes remained unchanged. AMPT provided students with the opportunity to express themselves and see their interests reflected in the math domain. After experiencing this level of agency over math content, their sense of belonging in mathematics increased. The results of this study demonstrate the potential for generative AI to enhance student choice, motivation, and, ultimately, achievement in mathematics.