The following are the baseball events of the year 1939 throughout the world.  

George Herman Ruth, Jr. (February 6, 1895 – August 16, 1948), best known as "Babe" Ruth and nicknamed "the Bambino" and "the Sultan of Swat", was an American baseball player who spent 22 seasons in Major League Baseball (MLB) playing for three teams (1914–1935). Known for his hitting brilliance, Ruth set career records for home runs (714), slugging percentage (.690), runs batted in (RBI) (2,217), and on-base plus slugging (OPS) (1.164). Ruth originally entered the major leagues with the Boston Red Sox as a starting pitcher, but after he was sold to the New York Yankees in 1919, he converted to a full time right fielder. He subsequently became one of the league's most prolific hitters and with his home run hitting prowess, he helped the Yankees win seven pennants and four World Series titles. Ruth retired in 1935 after a short stint with the Boston Braves, and the following year, he became one of the first five players to be elected into the National Baseball Hall of Fame.

Ruth was the first player to hit 60 home runs in one season (1927), a mark first eclipsed by Roger Maris in 1961 with 61. Ruth's lifetime record of 714 home runs stood until 1974 when it was surpassed by Hank Aaron. Unlike many power hitters, Ruth also hit for a high batting average: his .342 lifetime average is the tenth highest in baseball history, and in one season (1923) he batted .393, a Yankee record. Ruth dominated the era in which he played. He led the league in home runs during a season twelve times, slugging percentage and OPS thirteen times each, runs scored eight times, and RBIs six times. Each of those totals represents a modern record.

Denton True "Cy" Young (March 29, 1867 – November 4, 1955) was an American Major League Baseball pitcher. During his 22-year baseball career (1890–1911), he pitched for five different teams. Young established numerous pitching records, some of which have stood for a century. Young compiled 511 wins, which is most in Major League history and 94 ahead of Walter Johnson who is second on the list. Young was elected to the National Baseball Hall of Fame in 1937. One year after Young's death, the Cy Young Award was created to honor the previous season's best pitcher.

In addition to wins, Young still holds the Major League records for most career innings pitched (7,355), most career games started (815), and most complete games (749). He also retired with 316 losses, the most in MLB history. Young's 76 career shutouts are fourth all-time. He also won at least 30 games in a season five times, with ten other seasons of 20 or more wins. In addition, Young pitched three no-hitters, including the third perfect game in baseball history, first in baseball's "modern era". In 1999, 88 years after his final Major League appearance and 44 years after his death, editors at The Sporting News ranked Cy Young 14th on their list of "Baseball's 100 Greatest Players". That same year, baseball fans named him to the Major League Baseball All-Century Team.

Charles Ernest "Charlie" Keller (September 12, 1916 – May 23, 1990) was a left fielder in Major League Baseball. From 1939 through 1952, Keller played for the New York Yankees (1939–43, 1945–49, 1952) and Detroit Tigers (1950–51). A native of Middletown, Maryland, he batted left-handed and threw right-handed.

For much of ten American League seasons, Keller joined with Joe DiMaggio and Tommy Henrich to form one of the best-hitting outfields in baseball history. A splendid all-round athlete at the University of Maryland, where he earned a degree in agricultural economics in 1937, Keller joined the Yankees in 1939 and quickly became the regular left fielder, with Henrich patrolling right field and DiMaggio in center.

Through of his career, Keller was a feared slugger and a competent fielder. In his rookie season he hit .334 with 11 home runs and 83 RBI in 111 games. He hit three homers and batted .438 as the Yankees swept four games from the Cincinnati Reds in the World Series.

In his sophomore season, Keller hit .286 with 21 home runs, 93 RBI, 18 doubles and 15 triples. His most productive season came in 1941, when he hit .298 and posted career-highs in home runs (33), RBI (122), and triples (15).

Giuseppe Paulo "Joe" DiMaggio (/dɨˈmɑːʒioʊ/ or /dɨˈmædʒioʊ/; November 25, 1914 – March 8, 1999), nicknamed "Joltin' Joe" and "The Yankee Clipper", was an American Major League Baseball center fielder who played his entire 13-year career for the New York Yankees. He is perhaps best known for his 56-game hitting streak (May 15 – July 16, 1941), a record that still stands. DiMaggio was inducted into the Baseball Hall of Fame in 1955.

A three-time MVP winner and 13-time All-Star, DiMaggio is the only player to be selected for the All-Star Game in every season he played. During his thirteen years with the Yankees, the club won ten American League pennants and nine World Series championships.

At the time of his retirement, he ranked fifth in career home runs (361) and sixth in career slugging percentage (.579). He was voted the sport's greatest living player in a poll taken in the baseball centennial year of 1969.

His brothers Vince and Dom also became major league center fielders.

DiMaggio was born in Martinez, California, the eighth of nine children born to immigrants from Italy, Giuseppe (1872–1949) and Rosalia (Mercurio) DiMaggio (1878–1951). He was delivered by a midwife identified on his birth certificate as Mrs. J. Pico. He was named after his father; "Paolo" was in honor of Giuseppe's favorite saint, Saint Paul. The family moved to San Francisco, California, when Joe was a year old.