Gardner was a major leader in the Yankees' clubhouse during his tenure and developed into a fan favorite due to his tenacity, grit, and blue-collar approach.

[4] In 2005, his senior year, he batted .447, tied for the most hits in college baseball with 122, established a Cougars record with 85 runs scored, and led the Southern Conference with 38 stolen bases.

[12] Playing for Scranton/Wilkes-Barre in 2008, in 94 games Gardner was second in the International League with a .414 on-base percentage, 70 walks, 11 triples, and was sixth in the IL with 37 stolen bases, while being caught only nine times.

On July 2, he earned both his first pop out and first hit by pitch, off fellow rookie Texas Rangers relief pitcher Warner Madrigal in the seventh inning.

On July 26, 2008, Gardner was optioned back to AAA after the acquisition of Xavier Nady in order to continue to receive playing time.

[15][20] On December 7, 2010, Gardner underwent surgery to get rid of inflamed tissue in his wrist, with Yankees general manager Brian Cashman stating that he would be back in time for spring training.

However, after Jeter was put on the disabled list for a calf injury, Gardner was returned to the top of the order, alternating with Nick Swisher.

[25] On July 24, Gardner underwent right elbow surgery, performed by Christopher S. Ahmad, to remove a bone spur and inflamed tissue.

[15] With Curtis Granderson having suffered a fractured right forearm during a spring training game, Gardner was moved to center field for the 2013 season.

[28] On August 11, 2013, Gardner hit his first career walk-off home run with two outs in the bottom of the ninth inning off of Detroit Tigers reliever José Veras.

The home run sealed a 5–4 victory for the Yankees, and helped give support to a struggling Mariano Rivera, who blew three consecutive save opportunities for the only time in his career.

In the same series against Detroit two days earlier, Gardner made his first bailout of Rivera's pitching mishap by hitting a walk-off single past a diving Miguel Cabrera to give the Yankees a 4–3 win.

According to the Elias Sports Bureau, Gardner became the first Yankee since Claudell Washington in 1988 to have two walk-off hits in a span of three or fewer games.

[29] In 2013, Gardner played 145 games batting .273 with eight home runs, 33 doubles, an American League leading 10 triples, 52 RBI, and 24 stolen bases.

On July 28, 2014, Gardner recorded his first career multi-homer game where he hit two home runs off of Texas Rangers pitcher Yu Darvish.

[33] Gardner struggled in September due to an injury, finishing 12-for-72 (.167 batting average), dampening his strong 2014 offensive season.

For the 2014 season, Gardner played in 148 games, batting .256 with a career-high 17 home runs, 58 RBI, and 21 stolen bases, and had the highest number of pitches per plate appearance in the major leagues (4.44).

[36] After the 2014 season, Gardner underwent surgery in his right arm to correct a rectus abdominis muscle injury that affected him in July and September.

[44] On April 12, 2017, Gardner collided with Rickie Weeks of the Tampa Bay Rays at first base, and both players left the game.

[49] On June 30, Gardner went 3-for-5 with a grand slam and 6 RBIs, tying his career high, while falling a triple short of the cycle.

[53] Gardner hit 21 home runs, recording 23 steals and a .264 average as the Yankees made the playoffs and finished one game shy of the World Series.

However, due to injuries to Jacoby Ellsbury, (who missed the entire 2018 season with various ailments), Clint Frazier, who suffered a concussion in spring training that sidelined him for most of the season, and Aaron Judge (who missed two months with a wrist injury), Gardner saw more playing time than originally expected, appearing in 140 games.

[59] Despite once again starting the season as a projected fourth outfielder, due to injuries to Aaron Hicks, Gardner played in 140 games and hit .222 with 10 home runs and 39 RBI.

[61] In October 2022 a New Jersey paper reported that he had received a $6M offer from the Toronto Blue Jays but preferred to have returned to the Yankees.