Anand, the country's first Grandmaster, said it was a fantastic accomplishment on the part of Negi, who is currently the youngest GM in the world at 13 years, four months and 20 days and second youngest in the history of the game after Sergey Karjakin of Ukraine.
Karjakin achieved the feat at the age of 12 years and seven months.
"It is fantastic. To become second youngest ever Grandmaster is a great accomplishment and that too with six out of nine points is absolutely great," Anand told PTI over phone reacting to Negi's feat.
Negi also matched Anand's feat of grabbing all the norms in around six months.
Anand, the world number two, praised Negi for being focussed and hardworking and said that only by constantly playing can one's game be enhanced.
"He is growing fast. He is very active and that's excellent. By constantly playing you can know more about what you are doing is right or wrong. He does not even stop to celebrate his successes and is constantly working.
"He is playing as many tournaments as possible and that is very good for him," he said.
Negi, who achieved the feat on Saturday at Chelyabinsk Region Super final GM tournament in Russia, has straightaway headed to Athens to work with English Grandmaster Nigel Short and will return home only next month after playing a few more European tournaments.
The Madrid-based player said Negi had all-round talent in the game but lacked experience needed for handling crucial situations.
"When you are young, your style changes very fast. But he is fairly all-round.
"For instance, in Corus I noticed sometimes he plays well but let slips away opportunities," he said.
But Anand said he was impressed to see how the young player dealt with his mistakes.
"I am impressed with his attitude and approach towards the game. He looks at his mistakes objectively and that is very good." Asked what advise he would like to give to the promising youngster, he said "keep working hard".
Anand said Negi's feat would definitely help India on the international scene.
"It is great for India to have the second youngest ever player under its banner otherwise it was Ukraine to have the youngest player," he said.
Asked about his slipping out of the elite 2800 ELO club, Anand said "I am not affected (by the drop in ratings). I just want to play and let the ratings take care of themselves.
"I would now do some training and will play in Meinz and then against (top ranked junior) Rajdabov Teimour (of Azerbaijan) in August.