Gukesh stunned China's Ding Liren on Thursday when he seized upon an unfortunate blunder to win the last game of the World Chess Championship and clinch the title in Singapore.
As Ding faltered at the final hurdle of his title defence, an emotional Gukesh surpassed a record held by Russia's Garry Kasparov, who won the title at age 22.
He also became the second Indian to hold the title after five-time world champion Viswanathan Anand.
Fans in India hailed their new sporting hero while coaches said the win will pull in more talent.
"More people favour cricket in India but Gukesh's win will serve as a catalyst for parents to get their children into chess," Byomkesh, a chess coach who goes by one name, told AFP.
A chess academy in capital New Delhi was buzzing with activity a day after Gukesh's triumph, with students still recounting his best moves.
"Gukesh is a very hard-working guy who played the world championship very smoothly after the first game loss," 12-year-old Mahir Taneja told AFP.
"I dream to see myself also as a world champion like him and follow his steps."
Mahir's fandom proved infectious to his family.
"I'm also learning a lot of things and yesterday witnessing Gukesh win, I literally had goosebumps when my child comes and tells me each and every minute detail after every match that Gukesh and Ding had," said his mother Mani Taneja.
"And obviously, it's a proud moment for all of us."
'Dream big and work harder'
Gukesh was born to a doctor father and microbiologist mother in the southern Indian city of Chennai. He became India's youngest grandmaster aged 12 years, seven months and 17 days -- among the youngest in the history of the game.
In April, he became the youngest-ever winner of the prestigious Candidates Tournament, clinching his entry into the world championship.
The victory saw his name suddenly appear in the back pages of national newspapers alongside some of India's most recognisable sports stars, including Virat Kohli and Rohit Sharma.
Students at Gukesh's school in Chennai waved placards and photos of their newly famous alumni on Friday to celebrate his world title.
"Gukesh, you have made us so proud, and you are inspiring us to dream big and work harder," 14-year-old Emily Judith Samuel told AFP.
"You have checkmated the world... May success follow you everywhere you go."
Fellow student Bhavagna said Gukesh "will inspire and motivate the next generation of students to come. From the classrooms to his chessboard, he has taught us the true value of hard work".
According to Indian media, Gukesh left full-time schooling at the age of 10 to devote more time to chess training.
The southernmost Indian state of Tamil Nadu has declared a cash reward of $590,000 for Gukesh, supplementing the $1.35 million he won in Singapore.
