Antón Guijarro won the Spanish Youth Chess Championship in 2009, 2010, and 2012, and earned a silver medal at the World U16 Chess Championship in 2011. He also won the Spanish Chess Championship in 2016, 2017, and 2018. He was part of the Spanish team that placed fifth in the 2013 European Team Chess Championship.
Interestingly, Antón Guijarro has twice placed first in the prestigious Tradewise Gibraltar Chess Festival in 2015 and 2017, and participated in the 2017 Chess World Cup. His chess success has led to recognition, such as when he was named Sportsman of the Year by the Madrid Chess Federation in 2015.