At a press conference here where the news was confirmed, Chhetri, who was accompanied by the All India Football Federation (AIFF) President Praful Patel, said he was happy to have got a once-in-a-life-opportunity to play for a club in Portugal, one of the top football-playing nation in the world.
"The nation where I play football is ranked 165th and I am going to play in a country which is fifth in the world. The club I am going to play for is one of the best in the world," Chhetri said.
Chhetri said he would work very hard during his stint with Sporting and make the experience count in the future.
"I will make sure that when I turn 40, I wouldn't say that I could have done better. I will give my best," said Chhetri, who had played for Mohun Bagan in the 2011-12 season.
Earlier, Sporting had issued a press release on their website confirming the deal.
"Sporting Clube de Portugal has officially opened its doors to the Indian market," the club said in its release.
Sporting eyes to gain ground in one of FIFA's most highly regarded markets and has welcomed Indian national team captain, Sunil Chhetri, to join the club's reserve side, the press release added.
Chhetri has reportedly signed a two-year deal with Sporting, which had players like Cristiano Ronaldo and Nani in its ranks in the past. This will be the Delhi boy's second stint with a foreign soccer side after his contract with Kansas City Wizards, a team in the Major League Soccer in the USA, in March 2010. He, however, did not make any appearance in the league matches during the season.
Chhetri had also undergone trials for European sides like Coventry City and Glasgow Rangers without much success. His move to the Queens Park Rangers did not click after he failed to collect a work permit.