Background/purpose. This study aims to examine the effects of integrated board game development and cooperative learning on pre-service mathematics teachers' mathematical reasoning, conceptual understanding, creativity, and teamwork skills in Thailand. Materials/methods. Using a mixed-methods approach within the PAOR (Planning--Action--Observation--Reflection) cycle of Classroom Action Research, 59 third-year pre-service teachers collaboratively designed twelve educational board games integrating arithmetic operations, equations, and geometry. Data were collected through teamwork evaluation forms, board game evaluation rubrics, and semi-structured interviews. For Results. The findings demonstrated significant positive effects on both objectives. mathematical reasoning and conceptual understanding, 94.72% of games achieved "very good" or "excellent" ratings for mathematical content integration. For creativity and teamwork skills, 94.91% of participants achieved "very good" or "excellent" teamwork performance levels. The twelve unique games showcased creative integration of mathematical content with engaging gameplay mechanics, while supporting essential 21st-century competencies. Conclusion. Board game development proved effective in mathematics teacher education, promoting mathematical connections, reflective learning, and professional identity. The integration successfully enhanced both cognitive and social development among pre-service mathematics teachers.