The study involved 27 eight-year-old pupils and assessed how their experiences in writing their own procedural algorithms influenced both their arithmetic skills and their attitudes towards mathematics. Adopting a mixed-methods design, the research drew upon multiple data sources, including observation notes, student-generated artefacts, semi-structured interviews, a mathematics attitude scale, and an arithmetic operational skills test. The findings indicate that encouraging pupils to write their own code and algorithms significantly enhanced their arithmetic proficiency; students performed operations more rapidly and accurately, cultivated their creativity, and exhibited a more positive disposition towards mathematics. These activities also contributed to pupils perceiving mathematics as more enjoyable and becoming more willing to share their mathematical thinking. Overall, the study demonstrates that algorithm- and coding-based activities can be effectively integrated into primary-school mathematics education, yielding positive effects on pupils’ mathematical skills and attitudes. This approach offers practical insights for educators aiming to enrich mathematics instruction, thereby strengthening both pedagogical practice and student engagement.