The Reds promoted Hamilton to the major leagues on September 2, 2013, and made his debut on September 3 against the St. Louis Cardinals as a pinch runner for Ryan Ludwick.
He stole second base off Yadier Molina, and came around to score on a Todd Frazier double.
Hamilton appeared in four major league games as a pinch runner until September 10 when, in the seventh inning, he replaced Shin-Soo Choo in center field and also made his batting debut, going 0-for-2 in a loss at home to the Chicago Cubs.

Hamilton made his first start on September 18, 2013, in a Reds road win over the Houston Astros.
Playing center field and batting ninth, in his first at-bat of the game he notched his first Major League hit, a second-inning double to left field off Astros' starter Brad Peacock, and later got his first run batted in, driving in Todd Frazier with an infield single.
For the game (which went 13 innings), Hamilton reached base five times, going 3-for-4 with two walks, two runs scored, one RBI, and four stolen bases in four attempts off four pitchers.
Hamilton became the first Major League player since 1920 to steal four bases in his first Major League start.
In his first 10 times on base, he stole nine bases and scored six runs.
He was successful in his first 13 steal attempts, before being thrown out on his 14th attempt.

Hamilton became a regular with the Cincinnati Reds in 2014.
He had something of a rough start to the season, hitting just .221 through April 27 and being caught in five of his first 15 attempts at stealing.
By around the time of the All-Star break, however, Hamilton's stats had greatly improved and he was attracting positive attention from a number of sources, tipped as a potential Gold Glove candidate for defense and also noted for unexpected power hitting.
On September 2,  Hamilton, with his 55th stolen base of the season, set a Cincinnati Reds franchise record for most stolen bases in a season by a rookie, edging out the mark of 54 set in 1909 by Bob Bescher.
Despite this, Hamilton was second in Major League Baseball for stolen bases at the time, with Dee Gordon having recorded 58.
For the season, he batted .250/.292/.355 with 56 stolen bases while leading the league in being caught stealing, with 23.
On October 23, Hamilton was nominated for the 2014 Gold Glove for National League Center field, but lost to Juan Lagares of the New York Mets.
Hamilton also finished 2nd in NL Rookie of the Year voting, losing out to New York Mets pitcher Jacob DeGrom.

At the opening of the 2015 season, Hamilton joined Vince Coleman (1987) as the only players in Major League Baseball history to steal six bases in their team's first three games.
In the following game, he stole a seventh base, again matching Coleman for a record by being one of two players to steal seven bases within the first four games of the season.
He ended the season hitting .226/.274/.289 with 8 doubles and 3 triples (all career lows) and 57 stolen bases in 412 at bats.
Balls he hit had the lowest average exit velocity of any major leaguer (79.3 miles per hour), and he had the ninth-fastest sprint speed among major leaguers (29.7 feet per second).

In 2016, Hamilton hit a career-best .260 with a career-low 3 home runs and 17 RBIs in 119 games, going 58/66 in stolen bases.
Balls he hit had the second-lowest average exit velocity of any major leaguer (80.0 miles per hour), and he had the sixth-fastest sprint speed among major leaguers (30.2 feet per second).

On May 4, 2017, Hamilton stole his 200th career base.
He ended the season batting .247/.299/.335 while establishing career bests in at bats (582), runs (85), hits (144), triples (11), and a career high in strikeouts (133).
He also went 59/72 in stolen base attempts.
Balls he hit had the second-lowest average exit velocity of any major leaguer (78.6 miles per hour), and he had the sixth-fastest sprint speed among major leaguers (30.1 feet per second).

In 2018, Hamilton led all NL outfielders with 12 assists, but struggled offensively all season, hitting just .236/.299/.327 with 132 strikeouts while going 34/44 i
The Reds promoted Hamilton to the major leagues on September 2, 2013, and made his debut on September 3 against the St. Louis Cardinals as a pinch runner for Ryan Ludwick. He stole second base off Yadier Molina, and came around to score on a Todd Frazier double. Hamilton appeared in four major league games as a pinch runner until September 10 when, in the seventh inning, he replaced Shin-Soo Choo in center field and also made his batting debut, going 0-for-2 in a loss at home to the Chicago Cubs.
Hamilton made his first start on September 18, 2013, in a Reds road win over the Houston Astros. Playing center field and batting ninth, in his first at-bat of the game he notched his first Major League hit, a second-inning double to left field off Astros' starter Brad Peacock, and later got his first run batted in, driving in Todd Frazier with an infield single. For the game (which went 13 innings), Hamilton reached base five times, going 3-for-4 with two walks, two runs scored, one RBI, and four stolen bases in four attempts off four pitchers. Hamilton became the first Major League player since 1920 to steal four bases in his first Major League start. In his first 10 times on base, he stole nine bases and scored six runs. He was successful in his first 13 steal attempts, before being thrown out on his 14th attempt.
Hamilton became a regular with the Cincinnati Reds in 2014. He had something of a rough start to the season, hitting just .221 through April 27 and being caught in five of his first 15 attempts at stealing. By around the time of the All-Star break, however, Hamilton's stats had greatly improved and he was attracting positive attention from a number of sources, tipped as a potential Gold Glove candidate for defense and also noted for unexpected power hitting. On September 2,  Hamilton, with his 55th stolen base of the season, set a Cincinnati Reds franchise record for most stolen bases in a season by a rookie, edging out the mark of 54 set in 1909 by Bob Bescher. Despite this, Hamilton was second in Major League Baseball for stolen bases at the time, with Dee Gordon having recorded 58. For the season, he batted .250/.292/.355 with 56 stolen bases while leading the league in being caught stealing, with 23. On October 23, Hamilton was nominated for the 2014 Gold Glove for National League Center field, but lost to Juan Lagares of the New York Mets. Hamilton also finished 2nd in NL Rookie of the Year voting, losing out to New York Mets pitcher Jacob DeGrom.
At the opening of the 2015 season, Hamilton joined Vince Coleman (1987) as the only players in Major League Baseball history to steal six bases in their team's first three games. In the following game, he stole a seventh base, again matching Coleman for a record by being one of two players to steal seven bases within the first four games of the season. He ended the season hitting .226/.274/.289 with 8 doubles and 3 triples (all career lows) and 57 stolen bases in 412 at bats. Balls he hit had the lowest average exit velocity of any major leaguer (79.3 miles per hour), and he had the ninth-fastest sprint speed among major leaguers (29.7 feet per second).
In 2016, Hamilton hit a career-best .260 with a career-low 3 home runs and 17 RBIs in 119 games, going 58/66 in stolen bases. Balls he hit had the second-lowest average exit velocity of any major leaguer (80.0 miles per hour), and he had the sixth-fastest sprint speed among major leaguers (30.2 feet per second).
On May 4, 2017, Hamilton stole his 200th career base. He ended the season batting .247/.299/.335 while establishing career bests in at bats (582), runs (85), hits (144), triples (11), and a career high in strikeouts (133). He also went 59/72 in stolen base attempts. Balls he hit had the second-lowest average exit velocity of any major leaguer (78.6 miles per hour), and he had the sixth-fastest sprint speed among major leaguers (30.1 feet per second).
In 2018, Hamilton led all NL outfielders with 12 assists, but struggled offensively all season, hitting just .236/.299/.327 with 132 strikeouts while going 34/44 i
Billy Hamilton (baseball, born 1990)