While still playing as first baseman, Grimm was enlisted to replace Rogers Hornsby as manager after his dismissal on August 2, 1932. The team was 53-46 at the time, five games back in the standings in second place. In the 55 games that Grimm managed for the Cubs, he rallied them to a 37-18 record for an overall record of 90-64, winning the National League pennantfor the first time since 1929. The Cubs were subsequently swept by the New York Yankees in the World Series. The team regressed in the following two seasons, winning 86 games each and finishing in third place. However, Grimm's team made a dramatic improvement in 1935, going 100-54. It was the first time the Cubs had won 100 games since 1910 and it was the last until 2016. They were bolstered by a 21-game winning streak in September that carried them to a second league pennant in four seasons. In the World Series that year against the Detroit Tigers, they won the first game in Detroit before losing the next three. They rallied to win Game 5 at Wrigley Field, but the Tigers won a walk-off hit from Goose Goslin to win 4-3 and seal the Series. The Cubs went 87-67 for a third place finish the following year, but they improved to 93-61 and second place the year after. 1938 was his last season of his first tenure as manager of the Cubs. The team was 45-36 when he was replaced by catcher Gabby Hartnett. As Grimm had done six years earlier, the newly installed player-manager led the Cubs to a dramatic comeback to win the league pennant that season. After a sluggish start by the Cubs in 1944 in which the team lost ten in a row after winning the Opening Day game, Grimm was hired to manage the club again. The team finished fourth in the standings with a 75-79 record. However, Grimm led them to a dramatic improvement the following year, going 98-56 to win the league pennant for the first time since 1938. In the World Series that year, Grimm's team faced off against the Tigers once again. It was a hard-fought series, going down to the decisive seventh game at Wrigley Field. The Cubs were trounced 9-3, with six of the Tiger runs coming in the first two innings. It was the last pennant for the Cubs for 71 years. The Cubs went 82-71 the following year, finishing 3rd in the standings. It was the last time the team had a record of.500 until 1963. Grimm finished his last three seasons with losing record before resigning in 1949. After his resignation from being manager, he served as the Cubs' Director of Player Personnel, then the club's title for general manager, doing so until February 1950 due to not feeling comfortable in his front-office post. He subsequently was hired to manage a Double A team, the Dallas Eagles of the Texas League. Grimm was also a major baseball figure in Milwaukee. He was hired by Bill Veeck to manage his Milwaukee Brewers, then the Cubs' top farm team, during World War II. He returned to the Brewers in 1951 when they were a farm team of the Boston Braves. He was highly successful as a manager during each term, winning the regular season American Association title in 1943 and 1951, and the playoff championship in 1951. On May 30, 1952, Grimm was promoted from Milwaukee to manager of the big league Braves; he would prove to be the last skipper in the history of the Boston NL club. He went 51-67 as the Braves finished seventh place. He then managed the Milwaukee Braves for their first three years after their move to Wisconsin in March 1953. Being of German extraction, he was popular in the Beer City. The following year, the Braves went 92-62, finishing 13 games behind in second place to the Brooklyn Dodgers. It was the first time the Braves had won over 90 games since 1948. The next year, they regressed a bit as a team with an 89-65 record for a third place finish, but it was the first time that they had consecutive winning seasons since 1947-48. The next year, they went 85-69, finishing 13.5 games back of the Dodgers. The 1956 season proved to be a nail-biter for the team, but Grimm was not to be a big part of said season. He was dismissed after a 24–22 start to the season, replaced by Fred Haney. Haney led them to a 68–40 record while losing the league pennant to the Dodgers by one game. Haney led the team to a World Series championship the following year. He was brought out of retirement to direct the Cubs again in early 1960, but the team got off to a slow start, and owner P.K. Wrigley made the novel move of swapping Grimm with another former manager, Lou Boudreau, who was doing Cubs radiocasts at that time. Grimm had done play-by-play in the past, so he gave it one more go in 1960, before stepping back to the ranks of coaching and then front office duties. It was in 1961 that Wrigley began his "College of Coaches", of which Grimm was a part but was never designated "Head Coach". One of the Cubs' coaches during that 5-year experiment was baseball's first black coach, Buck O'Neil. Grimm finished with a record of 1,287 wins and 1,067 losses in the regular season and five wins and 12 losses in the post-season. His 946 wins as Cubs manager rank second behind Cap Anson.
