In January 2018, Praggnanandhaa tied for third place with GM Alder Escobar Forero and IM Denys Shmelov in the Charlotte Chess Center's Winter 2018 GM Norm Invitational held in Charlotte, North Carolina, with a score of 5.0/9. In the last game, So defeated Praggnanandhaa, winning the match 2½–1½. He defeated So in game one, and after three games the score was tied at 1½–1½.
In 2018, Praggnanandhaa was invited to the Magistral de León Masters in Spain for a four-game rapid match against Wesley So. He is the fifth-youngest person ever to achieve the title of Grandmaster (GM), behind Abhimanyu Mishra, Sergey Karjakin, Gukesh D, and Javokhir Sindarov. On 23 June 2018 he achieved his third and final norm at the Gredine Open in Urtijëi, Italy, by defeating Luca Moroni in the eighth round to become, at the age of 12 years, 10 months and 13 days, the then second-youngest person ever to achieve the rank of grandmaster (Karjakin attained the title at 12 years and 7 months). He gained his second norm at the Heraklion Fischer Memorial GM norm tournament in Greece on 17 April 2018. He achieved his first grandmaster norm at the World Junior Chess Championship in November 2017, finishing fourth with 8 points. In 2016, Praggnanandhaa became the youngest international master in history, at the age of 10 years, 10 months, and 19 days. Praggnanandhaa won the World Youth Chess Championship Under-8 title in 2013, earning him the title of FIDE Master at the age of 7.