[3] Green transferred to a charter school, Gulf Shores Academy in Houston where he repeated his junior year.

Green also won the McDonald's All-American Slam Dunk Contest that year, defeating future Duke player Josh McRoberts.

[5] Green originally committed to Oklahoma State University, but later decided to enter the NBA draft upon graduation.

Green was expected by many analysts to be one of the top players chosen but he fell to the Celtics, who selected him with the 18th pick in the 2005 NBA draft.

[6] After seeing limited playing time during the first part of the season, Green was placed on the Fayetteville Patriots of the NBA D-League by the Celtics in January 2006.

He was recalled and activated again on February 21, and saw his first significant NBA game action on the following night, scoring 13 points and grabbing 9 rebounds in 23 minutes.

On February 17, 2007, Green won the 2007 NBA Slam Dunk Contest, beating out Nate Robinson, Tyrus Thomas, and Dwight Howard.

[7] On July 31, 2007, it was made official that Green was to be traded along with Al Jefferson, Ryan Gomes, Theo Ratliff, Sebastian Telfair, and draft picks, to the Minnesota Timberwolves for Kevin Garnett.

[11][12] On February 21, 2008, Green was traded to his hometown team Houston Rockets for Kirk Snyder, a 2010 second-round draft pick, and cash considerations.

His agent Colin Bryant told Fox 26 Sports, "We have a verbal agreement with Dallas on a one year contract, We talked to a number of teams and there is more money out there, but this is the best situation for Gerald at this point in his career.

"[14] Green was not supposed to go to the summer league, but chose to go to learn the plays and get a feeling of the Mavericks organization early and not let his chance slip away.

His dunk against the Houston Rockets on March 10, 2012, was called "one of the dirtiest in-game windmill alley-oops in NBA history".

On July 27, 2013, Green was traded to the Phoenix Suns alongside Miles Plumlee and a future first-round pick for Luis Scola.

[24] Green started for the Suns when fellow guards Goran Dragić and Eric Bledsoe were injured during their respective periods in November 2013.

He received more starting time with the Suns after Bledsoe had a major knee injury during January, February, and early March 2014.

As a result, he finished fourth in the NBA Most Improved Player Award behind Anthony Davis, Lance Stephenson, and Green's teammate Goran Dragić.

[28] He made his debut for the Heat in the team's season opener against the Charlotte Hornets on October 28, scoring 19 points off the bench in a 104–94 win.

[29] On November 27, he scored a season-high 25 points while starting in place of the injured Luol Deng, helping the Heat defeat the New York Knicks 97–78.

[30] He topped that mark on April 1, 2016, scoring 30 points while starting in place of the injured Dwyane Wade, helping the Heat defeat the Sacramento Kings 112–106.

[33] On April 23, 2017, in Game 4 of the Celtics' first-round playoff series against the Chicago Bulls, Green had a postseason career-high 18 points, 16 of which were tallied before halftime.

[43] On October 28, the Rockets announced that Green had undergone surgery to repair a broken bone in his left foot and would be sidelined for approximately six months.

[51][52] Green drew comparisons to future Houston Rockets teammate and star Tracy McGrady in the period leading up to the 2005 NBA draft.