Raschi's debut on the New York Yankees was on September 23, 1946, wearing uniform number 12. The next year he wore three different numbers (17, 19, and 43) but number 17 became his from then on during his Yankee career. From 1946 to 1953, Raschi won 120 games while losing 50. He led the American League in won/lost percentage with a .724 record in 1950, and in strikeouts with 164 in 1951. Raschi had a .184 career batting average, with seven runs batted in (RBI) in one game, an American League record for pitchers, on August 3, 1953.
On February 24, 1954, Yankee fans were surprised to see Raschi traded to the St. Louis Cardinals. In the remaining two years of his career, with the Cardinals and Kansas City Athletics (who signed him as a free agent on April 28, 1955 when the Cardinals released him), Raschi won only 12 games while losing 16.
On April 23, 1954, while with the Cardinals, Raschi gave up the first of Hank Aaron's 755 career home runs. Aaron, Major League Baseball′s future home run king, had also notched his first career hit off Raschi eight days earlier.
He kept his uniform number 17 on the Cardinals, but on the A's took number 16.