More than 117,000 teachers have also been trained as part of a project to focus on the quality of education for the country's young students.
Three years ago, there was fewer than one maths textbook for every three children in Kenya's primary schools.
Now every student in grades 1, 2 and 3 has one - thanks to a programme that has delivered 7.6 million books into the country's classrooms.
More than 117,000 teachers have also been trained as part of the Primary Education Development Project (PRIEDE) since it was launched in 2015.
Kenya has shifted its emphasis from just getting children into school to focusing on the quality of education they receive, according to Principal Secretary for Basic Education Dr Belio Kipsang.
“It is not about access only. It is access and learning,” he said when he met a delegation from Malawi. Senior education officials have been in Kenya for 10 days to study how the government is working to ensure quality learning for every child through PRIEDE.
Dr Kipsang said it was crucial for early childhood development and pre-primary education to be integrated with primary and secondary schooling.
Theirworld has been campaigning for world leaders to invest 10% of education spending in pre-primary, which leaves children better prepared for primary school and less likely to drop out in later years.
PRIEDE - funded by the Global Partnership for Education - and the millions of maths textbooks are helping to change the face of primary school education in Kenya.
GPE Senior Education Specialist Fazle Rabbani said: "These books, along with a new teacher training programme, a school grants scheme and a new range of teacher performance assessments are changing the ecology of primary education in rural Kenya."
He went to Kenya recently to see the impact and wrote in a blog: "So far over 17,000 lessons have been observed by trained curriculum support officers. Data collected from classroom observations are also analysed to improve teacher training and textbooks.
"Expanding the lessons and benefits of the project to other subject areas and to other schools is the next challenge for Kenya."