Stoudemire's first name had previously been listed in the Phoenix Suns media guide as Amaré or Amare, but it was changed to Amar'e in October 2008. Stoudemire told NBA.com that his name had always been spelled Amar'e, but the media had been spelling it incorrectly since he joined the NBA.
As a result, he attended six different high schools—among them Mount Zion Christian Academy—before graduating from Cypress Creek High School in Orlando, Florida. He told Isaac Perry in an article for Dime Magazine that what kept him going in that time period was God and the words of rapper Tupac Shakur.
Instead, he declared for the NBA draft because of his desire to help his family quickly. The Phoenix Suns decided on him with the ninth pick in the 2002 NBA Draft due to a need for inside strength at the time. Phoenix was the only team that year to select a high school player in the first round.
In his rookie season, Stoudemire averaged 13.5 points and 8.8 rebounds per game, with a season high of 38 points against the Minnesota Timberwolves on December 30, 2002, the highest score by a prep-to-pro player until broken a year later by LeBron James. Stoudemire won the NBA's Rookie of the Year award, beating out Yao Ming and Caron Butler and becoming the first player drafted out of high school to win the award.The following season, Stoudemire improved statistically, but his team stumbled to a 29–53 record, and point guard Stephon Marbury was traded to the New York Knicks. During the summer of 2004, Stoudemire was selected to play for the eventual Bronze Medal-winning United States national team in the 2004 Summer Olympics. However, head coach Larry Brown declined to give him significant playing time
During the 2004–05 NBA season, Stoudemire teamed up with point guard Steve Nash to lead the Suns to a 62–20 record. Averaging 26 points per game that year and achieving a new career high of 50 points against the Portland Trail Blazers on January 2, 2005, he was selected to his first National Basketball Association All-Star Game as a reserve forward. In the Western Conference Finals against the San Antonio Spurs, Stoudemire performed magnificently, averaging 37 points per game, but the Suns lost in 5 games.