An enrolled member of the Colorado River Indian Tribes, Ellsbury is the first Native American of Navajo descent to play Major League Baseball.

After having played college baseball for three years at Oregon State University, he was selected in the 1st round by the Red Sox, as the 23rd overall pick in the 2005 draft.

He led the American League in stolen bases three times (in 2008, 2009, and 2013) and won World Series championships as a member of the Red Sox in 2007 and 2013.

He ended his playing days as the single season and career record holder for reaching base via catcher's interference.

The Ellsburys lived on the Warm Springs Indian Reservation until they moved to Madras, Oregon, when Jacoby was in kindergarten.

He went to Oregon State University where he was a Baseball America first-team All-American and Pac-10 Conference Co-Player of the year, with Trevor Crowe.

[12] Ellsbury began the 2006 season ranked by Baseball America as the sixth-best prospect in the Red Sox' organization.

[26] The 2007 Baseball America Prospect Handbook compared Ellsbury to former Red Sox center fielder Johnny Damon, lauding his speed, hitting and fielding while noting his below-average throwing arm.

[27] After Coco Crisp was injured, the Red Sox purchased Ellsbury's contract and he received a call-up on June 30, in which he made his MLB debut in center field and hit ninth against the Texas Rangers at Fenway Park[28] wearing number 46.

Ellsbury's first career stolen base came off pitcher Brandon McCarthy and catcher Gerald Laird of the Rangers on July 2.

[31] On August 17, the Red Sox recalled Ellsbury from Pawtucket for the second game of a doubleheader, in which he led off and played center field.

[35] A September 2007 article in The New York Times described him as a "cult hero" who brings "speed, improved defense, and unbridled enthusiasm.

[38] The Red Sox eventually won the World Series in a four-game sweep over the Rockies, giving Ellsbury his first career championship title.

[46] Ellsbury stole his 32nd base of the season on June 15, breaking the Red Sox' rookie record, set 100 years earlier by Amby McConnell.

[38] Ellsbury finished third in the AL Rookie of the Year voting, behind Evan Longoria of Tampa Bay and Alexei Ramírez of the Chicago White Sox.

[38] In the second inning of Game 3 of the ALDS, he hit the first three-run single in postseason history when Howie Kendrick and Torii Hunter let a pop-up fall to the ground between them.

In 2008, Ellsbury was one of three active non-Hispanic Native American players in Major League Baseball, along with Kyle Lohse and Joba Chamberlain.

[51] Ellsbury played his 179th straight regular-season game without an error on April 12, 2009, breaking the franchise record for outfielders held by Mike Greenwell.

[57] During the offseason, Ellsbury changed his uniform number from 46 to 2, which had belonged to the Red Sox' former bench coach, Brad Mills, who left the organization to become the manager of the Houston Astros.

[59] On April 11, Ellsbury collided with Red Sox third baseman Adrián Beltré in a game against the Kansas City Royals, and the collision resulted in hairline fractures to four of his left ribs.

On September 25, he hit two home runs during the first game of a doubleheader against the Yankees to become the first member of the Boston Red Sox to join the 30–30 club.

[66][67][68] He won his first Gold Glove Award, and finished as one of only two qualifying players to complete the season with a 1.000 fielding percentage.

[72] He was activated from the DL and returned to the Red Sox lineup on July 13,[73] and finished the season with a .271 batting average, four home runs, 26 RBI, and 14 stolen bases in only 74 games played.

[75] He was taken to the Steadman Clinic in Vail, Colo., for treatment from Dr. Thomas Clanton, who cleared him to rejoin the Red Sox lineup on September 25, well ahead of the preliminary prognosis.

[81] On April 22, 2014, Ellsbury played his first game at Fenway Park since leaving the Red Sox to join the Yankees.

[86] On April 22, 2016, Ellsbury executed a straight steal of home against Matt Moore of the Tampa Bay Rays during a full count, tying the game at 3.

On July 20, Ellsbury reached base via catcher's interference for the ninth time in the season, setting a new single-season MLB record.

[65] On April 28, 2017, Ellsbury hit his first career grand slam against the Baltimore Orioles in a 14-11 Yankees comeback win.

"[110] Ellsbury was one of the victims of the $8 billion fraud perpetrated by wealth manager Allen Stanford;[111] although he had some assets frozen, it did not cause him any significant hardship akin to those suffered by Johnny Damon and Xavier Nady.

The wine launched alongside a charity wine by former Boston Red Sox teammate Josh Beckett, called Chardon-K.[114] In June 2014, Ellsbury donated $1 million to his alma mater Oregon State University as part of a $3 million renovation project at Goss Stadium.