Iniyan was introduced to chess at the age of five, and grew up in a family with a sports-oriented background. At age six he finished second in the national under-7 event, which qualified him for Asian and World Youth competitions in the under-8 category, securing a silver medal at the Commonwealth under-8 championship. At age 13 he won the Indian under-15 championship. 

In July 2017, at age 14, Iniyan made his breakthrough on the international stage by finishing fourth at the Andorra Open, defeating the top-seeded grandmaster and gaining 20.4 Elo points. His rating progressed steadily, and he earned his International Master title 2017. He gained the GM title in March 2019, becoming India's 61st grandmaster at the age of 16.