Cavaretta attended
Lane Technical High School on Chicago's North Side (now known as Lane Tech College Prep), where he played baseball and basketball, and signed a professional contract with the Cubs before finishing high school. In his first professional game with Peoria at age 17 in , Cavaretta
hit for the cycle as a
right fielder. That same year he was brought up to the Cubs to replace manager
Charlie Grimm at first base. He first appeared in a major league game on September 16, 1934, less than two months after his 18th birthday, pinch-hitting unsuccessfully for the Cubs' shortstop
Billy Jurges in the fifth inning of the first game of a doubleheader in Brooklyn. A week later, on September 25, in his first start and his first appearance at the Cubs' home park,
Wrigley Field, Cavaretta hit a
home run that supplied the winning margin in the Cubs' 1–0 win over Cincinnati. In his rookie season, he batted .275 with 82
runs batted in, also leading the league in
double plays, as the Cubs captured their third pennant in seven years by winning 21 straight games in September; however, he batted only .125 in the
World Series loss to the
Detroit Tigers. Over the next several seasons he provided solid play at first base, routinely batting between .270 and .291 every season but one through 1943, though he lost significant playing time from 1938 to 1940 due to a hip injury and an ankle broken twice while sliding. In the
1938 World Series against the
New York Yankees, he batted .462 as the Cubs were swept. Exempted from World War II service because of a perforated eardrum, in Cavaretta batted .321 with a league-high 197
hits, had career highs with 106
runs, 35
doubles and 15
triples, and earned his first of four straight
All-Star selections (reaching base a record five times in the game) though the Cubs suffered their fifth consecutive losing season. But the team improved by 23 games in 1945, edging the defending champion
St. Louis Cardinals by three games for the pennant as Cavaretta was named MVP. That season he won the National League batting title, hitting .355. He also had a career-high 97 RBI, leading the NL in
on-base percentage and finishing third in
slugging average. He batted .423 in the
World Series against the Tigers, though the Cubs again lost, in seven games. In Game 1, he singled and scored as the Cubs took a 4–0 lead in the first inning, singled and scored again in the third, and homered in the seventh as Chicago took the opener 9–0. He scored the Cubs' only run in Game 2, and in a 12-inning 8–7 win in Game 6 had a 2–RBI single and scored a run; he had three hits in Game 7, but the Cubs lost 9–3. He made the All-Star team again in 1946 and 1947, batting .314 the latter year, as the Cubs again fell back in the standings. He was named manager in June 1951, succeeding
Frankie Frisch. Continuing as manager for two more years, he compiled a record of 169–213. In , his final season with the Cubs, he surpassed
Stan Hack's modern team record of 1,938 games;
Ernie Banks would eventually break his mark of 1,953 games in . Cavarretta was fired during spring training after admitting the team was unlikely to finish above fifth place (they finished seventh), and in May he signed with the crosstown
Chicago White Sox; he ended his career there in . ==Legacy==