Schilling has won League Championship titles with three dark-horse teams; in 1993 with the Philadelphia Phillies (who overcame a last-place finish in the National League East in '92), in 2001 with the Diamondbacks (who became the youngest expansion team to win a title) and in 2004 with the Red Sox (who overcame a 0-3 deficit against the New York Yankees). He also went on to win World Series titles with two of them: the 2001 Diamondbacks and the 2004 Red Sox.

Schilling began his professional career as a prospect in the Boston farm system, but was traded to the Baltimore Orioles in 1988 for Mike Boddicker. His major league debut was with the Orioles (1988-1990), he spent one year with the Houston Astros (1991), and then spent more than eight seasons with the Philadelphia Phillies (1992-2000).

Schilling was one of the key factors in the Phillies' pennant run in 1993. In that year, Schilling went 16-7 with a 4.02 ERA and 186 strikeouts. Schilling then led the Phillies to an upset against the two-time defending National League champion Atlanta Braves in the National League Championship Series. Although he didn't get any decisions during his two appearances in the six game series, Schilling's 1.69 ERA and 19 strikeouts were still enough to earn him the 1993 NLCS Most Valuable Player Award. The Phillies went on to battle the defending World Champion Toronto Blue Jays in the World Series. Schilling was the losing pitcher in Game 1 but he redeemed himself greatly in Game 5. With the Phillies facing elimination the day after losing a bizarre 15-14 contest at home in Veterans Stadium, Schilling pitched a five-hit shutout that the Phillies won 2-0. Unfortunately, Schilling would soon watch helplessly from the dugout as the Phillies lost another heartbreaker to the Blue Jays.

He was traded mid-season to the Diamondbacks in 2000. With Arizona, he went 22-6 with a 2.98 ERA in 2001 and went 4-0 with a 1.12 ERA in the playoffs. In the 2001 World Series the Diamondbacks beat the New York Yankees in 7 games. Schilling shared the 2001 World Series MVP Award star with teammate Randy Johnson. He and Johnson also shared Sports Illustrated magazine's 2001 "Sportsmen of the Year" award. In 2002, he went 23-7 with a 3.23 ERA. Both years he finished second in the Cy Young Award voting to Johnson.

Schilling with the Boston Red Sox.In November 2003, the Diamondbacks traded Schilling to the Boston Red Sox. On September 16, 2004, Schilling won his twentieth game of the season for the Red Sox, becoming the fifth Boston pitcher to win 20 or more games in his first season with the team, and the first since Hall of Famer Dennis Eckersley in 1978. Schilling would go on to another win, ending his regular season with a 21-6 record.

On October 19, Schilling won Game 6 of the 2004 American League Championship Series against the New York Yankees. Notably, he won this game playing on an injured ankle - the same injuries that contributed to his disastrous outing in Game 1 of the ALCS. These injuries were so acute that by the end of his performance that day his white sock was soaked with blood.

The win forced a Game 7, making the Red Sox the first team in post-season Major League Baseball history to come back from a three-games-to-none deficit. The Red Sox would go on to win Game 7 and the ALCS and make their first World Series appearance since 1986. He pitched (and won) Game 2 of the 2004 World Series for the Red Sox against the St. Louis Cardinals. In both series, he had to have the tendon in his right ankle stabilized repeatedly, in what has become known as the Schilling Tendon Procedure, after the tendon sheath was torn during his Game 1 ALDS appearance against the Anaheim Angels. As in game 6 of the ALCS, Schilling's sock was soaked with blood from the sutures used in this medical procedure. This second "bloody" sock was placed in the Baseball Hall of Fame after Boston's victory over St. Louis in the World Series. A 4-game sweep of the World Series gave Boston its first World Series championship since 1918.

Schilling was once again runner-up in Cy Young voting in 2004, this time to Minnesota Twins hurler Johan Santana, who received all 28 first-place votes. Schilling received 27 of the 28 second-place votes. Later, the entire Red Sox team was named Sports Illustrated's 2004 Sportsmen of the Year, making Schilling only the second person to have won or shared that award twice. Schilling's ankle injury had an immense effect on his pitching performance in 2005. He began the year on the disabled list, and even when he returned, he simply wasn't the Curt Schilling everyone knew. His velocity was down, his control was off, and his signature splitter pitch didn't have much bite to it. After being placed on the disabled list again, he returned in July as Boston's closer. The idea was that Schilling would work out of the bullpen until gaining enough strength to rejoin the starting rotation. However, this experiment, for the most part, was unsuccessful. Schilling did earn some saves, but was mostly ineffective. He eventually returned to the starting rotation and continued to struggle. However, he did have an excellent start against the Yankees in a September game, which was easily the highlight of his season. The Red Sox made it to the playoffs, but were swept by the Chicago White Sox in three games. Schilling was set to start the fourth game, but never got the chance.

On Saturday, May 27, 2006, Schilling earned his 200th career win, the 104th major league pitcher to accomplish the feat. The Red Sox beat Tampa Bay, 6-4.