Following his successful rookie campaign, Toews was named team captain of the Blackhawks on July 18, 2008. At 20 years and 79 days, he became the third-youngest team captain in NHL history, behind Sidney Crosby of the Pittsburgh Penguins and Vincent Lecavalier of the Tampa Bay Lightning. Toews had previously been named an alternate captain in December 2007, during the 2007–08 season. In the subsequent season, he was voted as a starter, along with teammates Patrick Kane and Brian Campbell, for the 2009 NHL All-Star Game in Montreal. He netted his first career hat trick in the NHL on February 27, 2009, in a 5-4 overtime loss to the Pittsburgh Penguins. He finished the 2008–09 season with 69 points in 82 games, helping the Blackhawks to their first post-season appearance since 2002. Toews added 13 points in 17 playoff games as the Blackhawks advanced to the Western Conference Finals, where they were eliminated by the Detroit Red Wings in five games.
During the 2010 playoffs, Toews recorded his second career hat trick, along with two assists, leading the Blackhawks in a 7-4 playoff victory against the Vancouver Canucks on May 7, 2010. On June 9, 2010, Toews led Chicago to the franchise's first Stanley Cup championship since 1961, defeating the Philadelphia Flyers in the sixth game of the Finals. He became the second-youngest captain in the history of the NHL to win the Cup, behind Sidney Crosby who led the Pittsburgh Penguins to the championship the previous season. He scored seven goals and 29 points in the playoffs, and won the Conn Smythe Trophy as playoff MVP. By winning the Stanley Cup, he also became the youngest player, at 22 years old, to become a member of the Triple Gold Club (Olympic gold, Stanley Cup, World Championship).
In the off-season, Toews was selected to be the cover player for EA Sports' video game NHL 11 on June 21, 2010. It marked the first time in EA Sports history that two players of the same team were featured on a video game cover two years in a row, as Patrick Kane had been on the cover of NHL 10.