In 1947, the Dodgers called Robinson up to the major leagues six days before the start of the season. With Eddie Stanky entrenched at second base for the Dodgers, Robinson played his initial major league season as a first baseman. On April 15, Robinson made his major league debut at the relatively advanced age of 28 at Ebbets Field before a crowd of 26,623 spectators, more than 14,000 of whom were black. Although he failed to get a base hit, he walked and scored a run in the Dodgers' 5–3 victory. Robinson became the first player since 1884 to openly break the major league baseball color line. Black fans began flocking to see the Dodgers when they came to town, abandoning their Negro league teams.
Robinson was also derided by opposing teams. According to a press report, the St. Louis Cardinals threatened to strike if Robinson played and to spread the walkout across the entire National League. Existence of the plot was said to have been leaked by the Cardinals' team physician, Robert Hyland, to a friend, the New York Herald Tribune's Rutherford "Rud" Rennie. The reporter, concerned about protecting Hyland's anonymity and job, in turn leaked it to his Tribune colleague and editor, Stanley Woodward, whose own subsequent reporting with other sources protected Hyland. The Woodward article made national headlines. After it was published, National League President Ford Frick and Baseball Commissioner Happy Chandler let it be known that any striking players would be suspended. "You will find that the friends that you think you have in the press box will not support you, that you will be outcasts," Frick was quoted as saying. "I do not care if half the league strikes. Those who do it will encounter quick retribution. All will be suspended and I don't care if it wrecks the National League for five years. This is the United States of America and one citizen has as much right to play as another." Woodward's article received the E. P. Dutton Award in 1947 for Best Sports Reporting. The Cardinals players denied that they were planning to strike, and Woodward later told author Roger Kahn that Frick was his true source; writer Warren Corbett said that Frick's speech "never happened". Regardless, the report led to Robinson receiving increased support from the sports media. Even The Sporting News, a publication that had backed the color line, came out against the idea of a strike.
Robinson nonetheless became the target of rough physical play by opponents (particularly the Cardinals). At one time, he received a seven-inch gash in his leg from Enos Slaughter. On April 22, 1947, during a game between the Dodgers and the Philadelphia Phillies, Phillies players and manager Ben Chapman called Robinson a "nigger" from their dugout and yelled that he should "go back to the cotton fields". Rickey later recalled that Chapman "did more than anybody to unite the Dodgers. When he poured out that string of unconscionable abuse, he solidified and united thirty men."
Robinson did, however, receive significant encouragement from several major league players. Robinson named Lee "Jeep" Handley, who played for the Phillies at the time, as the first opposing player to wish him well. Dodgers teammate Pee Wee Reese once came to Robinson's defense with the famous line, "You can hate a man for many reasons. Color is not one of them." In 1947 or 1948, Reese is said to have put his arm around Robinson in response to fans who shouted racial slurs at Robinson before a game in Boston or Cincinnati. A statue by sculptor William Behrends, unveiled at KeySpan Park on November 1, 2005, depicts Reese with his arm around Robinson. Jewish baseball star Hank Greenberg, who had to deal with ethnic epithets during his career, also encouraged Robinson. Following an incident where Greenberg collided with Robinson at first base, he "whispered a few words into Robinson's ear", which Robinson later characterized as "words of encouragement." Greenberg had advised him to overcome his critics by defeating them in games. Robinson also talked frequently with Larry Doby, who endured his own hardships since becoming the first black player in the American League with the Cleveland Indians, as the two spoke to one another via telephone throughout the season.
According to a poll conducted in 1947, Robinson was the second most popular man in the country, behind Bing Crosby. In 1999, he was named by Time on its list of the 100 most influential people of the 20th century. Also in 1999, he ranked number 44 on the Sporting News list of Baseball's 100 Greatest Players and was elected to the Major League Baseball All-Century Team as the top vote-getter among second basemen. Baseball writer Bill James, in The New Bill James Historical Baseball Abstract, ranked Robinson as the 32nd greatest player of all time strictly on the basis of his performance on the field, noting that he was one of the top players in the league throughout his career. Robinson was among the 25 charter members of UCLA's Athletics Hall of Fame in 1984. In 2002, Molefi Kete Asante included Robinson on his list of 100 Greatest African Americans. Robinson has also been honored by the United States Postal Service on three separate postage stamps, in 1982, 1999, and 2000.
A jersey that Robinson brought home with him after his rookie season ended in 1947 was sold at an auction for $2.05 million on November 19, 2017. The price was the highest ever paid for a post-World War II jersey.