For May 2017, Correa was named the AL Player of the Month. He delivered a career-best five consecutive multiple-hit games from May 25−29, and totaled 14 such games on the month. In 26 games, he batted .386, eight doubles, seven home runs, 26 RBI and a 1.130 OPS. His batting average and RBI total led the AL, on-base percentage ranked third, hits and OPS fifth, and slugging tied for sixth. He was selected to play in his first MLB All-Star Game, held at Marlins Park in Miami. On July 18, it was revealed that he had suffered a torn ligament in his left thumb. He was ruled out for six to eight weeks.
On October 6, 2017, Correa hit his first home run of the 2017 postseason against the Boston Red Sox in Game 2 of the American League Division Series. Two days later, he would hit his second home run of the postseason. On October 14, he hit his third home run of the post season including a walk-off double leading the Astros to their second win of the ALCS series against the Yankees. Correa and the Astros offense slumped as they lost all three middle games at Yankee Stadium. The Astros won Game 7 by a score of 4−0, advancing to their second World Series in franchise history, to face the National League pennant-winning Los Angeles Dodgers. In Game 2, Correa, along with two Astros teammates–José Altuve and George Springer—and two Dodgers players–Charlie Culberson and Yasiel Puig—all homered in extra innings as the Astros prevailed, 7−6. The five home runs accounted for the most hit in extra innings of any single game in major league history.
Three years later, it was revealed in the Houston Astros sign stealing scandal that the Astros had broken MLB rules during their championship season. The team was punished for this, and Correa admitted that illegally stealing signs had been an advantage. Correa also apologized, saying "We were wrong for everything we did in 2017. It's not what we stand for. It's not what we want to portray as an organization, and we were definitely wrong about all that and we feel really sorry. We affected careers, we affected the game in some way, and looking back at it, it was just bad." Correa's apology was seen as much more sincere than those of his teammates, Jose Altuve and Alex Bregman. Correa received praise for his apology, while Altuve and Bregman were scrutinised for their apologies seeming too scripted.
Correa played for Puerto Rico in the 2017 World Baseball Classic. With Francisco Lindor playing shortstop and Javier Baez as the team's second baseman, Correa played as Puerto Rico's third baseman. Correa batted .333 during the tournament, with three home runs, nine RBIs, 10 runs scored, and two stolen bases, including a home run in the semifinals. Following the conclusion of the tournament, he was named to the 2017 All-World Baseball Classic team.
He is involved in charity work, including helping children in Houston after Hurricane Harvey and his hometown in Puerto Rico after Hurricane Maria damaged the island in 2017. In March 2020, Correa donated $500,000 in medical equipment to help the city of Houston during the COVID-19 pandemic.