Whiteside grew up with six siblings and a single mother. Born and raised in Gastonia, North Carolina, he attended three high schools in two years: Hunter Huss High School, Ashbrook High School, and Forestview High School.
For his junior year of high school in 2006–07, Whiteside moved in with his father in Newark, New Jersey, playing at East Side High School. After averaging 18 points, 10 rebounds and 5.5 blocked shots per game, Whiteside went back to North Carolina for the 2007–08 school year and attended Hope Christian Academy (Kings Mountain, North Carolina). In 2008–09, he played prep basketball at The Patterson School in Lenoir, North Carolina where he helped lead Patterson to a 34–2 record and a No. 1 national ranking with future Marshall teammate DeAndre Kane.
Whiteside was rated as the No. 19 center in the Class of 2009, according to Scout.com and ranked as the No. 87 recruit in the Class of 2009 by Rivals.com. He played in the 2009 Reebok All-American preview game, and was a member of both the United Celtics (NC) AAU Team and the New Jersey Panthers AAU team as a high schooler.
Whiteside chose Marshall over Charlotte, South Carolina, Kentucky, Auburn, and Mississippi State.
Whiteside came to Marshall University under the radar during the start of the 2009–10 season, but it did not take long for him to make national attention. He was spotlighted in the December 28 edition of ESPN The Magazine's College Basketball column after he amassed 14 points, 17 rebounds and nine blocked shots over 29 minutes in a 60–53 win over the Ohio University Bobcats on November 28. A few weeks later on December 12, Whiteside recorded the Thundering Herd's first triple-double in a 105–54 rout of the Brescia Bearcats, scoring 17 points, grabbing 14 rebounds and blocking 11 shots. Whiteside would go on to have two more triple-doubles on the year against the UCF Knights on January 13, and February 27. He finished the season as the nation's leader in blocked shots with 182, and he also broke the C-USA record held by Tulsa's Jerome Jordan for most blocked shots in a single season and the Marshall record for the most blocked shots in a single season and career all in his freshman year. The 182 blocks were also a national record for a freshman in a single season, topping 177 by BYU's Shawn Bradley in 1990–91.
On March 29, 2010, Whiteside declared himself eligible for the 2010 NBA draft, after Marshall head coach, Donnie Jones, accepted the head coaching job at Conference USA rival UCF Knights.
On June 24, 2010, Whiteside was selected by the Sacramento Kings with the 33rd overall pick in the 2010 NBA draft. On July 19, he signed a four-year, $3.8 million contract with the Kings. The first two years of the deal were guaranteed for $1.76 million.
On November 29, 2010, Whiteside was assigned to the Kings' D-League affiliate, the Reno Bighorns. Whiteside was recalled back to the Kings on January 9, 2011. On March 5, 2011, Whiteside had surgery to repair a partially torn tendon in his left knee, which sidelined him for the rest of the season. He only appeared in one game with the Kings during his rookie season.
On January 1, 2012, Whiteside was reassigned to the Reno Bighorns. On February 4, he was recalled by the Kings. On July 16, 2012, he was waived by the Kings.
On December 14, 2012, Whiteside was acquired by the Sioux Falls Skyforce. On January 4, 2013, he was traded to the Rio Grande Valley Vipers in exchange for Damian Saunders. After winning the D-League championship with the Vipers, he joined Amchit Club in Lebanon.
On May 26, 2013, Whiteside joined Chinese NBL team, the Sichuan Blue Whales. He appeared in 27 games for the club, averaging 25.7 points, 16.6 rebounds, 5.1 blocks and 1.4 steals per game. He helped the team win the 2013 NBL championship.
In November 2013, Whiteside signed with Al Mouttahed Tripoli of the Lebanese Basketball League. On April 30, 2014, he was released by the club. He returned to China the following month, where he joined Jiangsu Tongxi of the Chinese NBL. He parted ways with the club in June after appearing in 17 games.
On September 25, 2014, Whiteside signed with the Memphis Grizzlies, but was later waived on October 22. On October 30, he was reacquired by the Rio Grande Valley Vipers. Two days later, his rights were traded to the Iowa Energy. He officially joined the Energy on November 14, 2014. On November 19, he re-signed with the Grizzlies, but was waived again the next day. On November 22, he re-joined Iowa.
On November 24, 2014, Whiteside signed with the Miami Heat. On December 13, he was assigned to the Sioux Falls Skyforce, but was recalled two days later. On January 4, 2015, he recorded his first career double-double with 11 points, 10 rebounds and 5 blocks in an 88–84 win over the Brooklyn Nets.
On January 11, 2015, Whiteside recorded a then career-high 23 points, 16 rebounds, 2 steals and 2 blocks in a 104–90 win against the Los Angeles Clippers. On January 25, he recorded his first career triple-double with 14 points, 13 rebounds, and franchise record 12 blocks in a 96–84 win over the Chicago Bulls. In the process, Whiteside became just the fourth player in the previous 25 years with at least 12 points, 12 rebounds and 12 blocks in a game, and the first player since Manute Bol with 12 blocks off the bench in 25 minutes or less. Bol had 13 blocks in 23 minutes. On February 4, he scored a then career-high 24 points on 12-of-13 shooting along with 20 rebounds in a loss to the Minnesota Timberwolves. His 90% field goal shooting and his 20/20 night made him one of only four players in NBA history to achieve such a feat.
On March 2, 2015, Whiteside got into a fight with Alex Len of the Phoenix Suns. The following day, the NBA fined Whiteside $15,000 for his role in the altercation. On March 10, he was suspended for one game without pay for striking Kelly Olynyk during the Heat's March 9 loss to the Boston Celtics. He went on to finish fourth in the NBA Most Improved Player Award voting. During his first season with the Heat, Whiteside averaged a double-double with 11.8 points and 10 rebounds per game.
On November 1, 2015, Whiteside scored a then career-high 25 points in a 109–89 win over the Houston Rockets. On November 17, he recorded his second career triple-double with 22 points, 14 rebounds and 10 blocks in a loss to the Minnesota Timberwolves. He became the seventh player in NBA history with multiple points-rebounds-blocks triple-doubles. On November 23, in a game against the New York Knicks, Whiteside blocked five shots, giving him 63 through 13 games. The previous Heat record for blocks at this point of the season belonged to Alonzo Mourning, who had 50 to open the 1998–99 season. On December 9, he recorded three blocks against the Charlotte Hornets, thus opening the season with two or more blocks in all 20 games, trailing only Mark Eaton (24, 1988–89 with Utah) and Shaquille O'Neal (23, 1992–93 with Orlando) for longest streaks to start a season. His streak ended at 21 after he failed to record a block on December 13 against the Memphis Grizzlies.
On January 15, 2016, Whiteside recorded his third career triple-double with 19 points, 17 rebounds and 11 blocked shots in a 98–95 win over the Denver Nuggets. Between January 22 and February 2, he missed six games with a left hip injury. He returned to action on February 3, recording 10 points, nine rebounds and five blocks in 17 minutes off the bench in a 93–90 win over the Dallas Mavericks. Two days later, he recorded his third triple-double of the season and fourth of his career with 10 points, 10 rebounds and 10 blocked shots in 27 minutes off the bench in a 98–95 win over the Charlotte Hornets. On February 20, he recorded 25 points and 23 rebounds off the bench in a 114–94 win over the Washington Wizards, marking just the 11th time in NBA history that a player has had at least 20 points and 20 rebounds in a game off the bench. Whiteside also blocked two shots in that game, giving him 300 with the Heat in 94 games, which is the fastest a Heat player has reached the 300-block mark. Alonzo Mourning was the previous fastest as he needed 108 games to accomplish the feat. In the Heat's next game the following day against the Indiana Pacers, Whiteside grabbed his 1,000th career rebound in his 95th game, marking the fastest anyone has reached that milestone in Heat history, ahead of Alonzo Mourning (96), Kevin Willis (98) and Shaquille O'Neal (99). On March 1, he recorded a career-high 26 points and 14 rebounds in a 129–111 win over the Chicago Bulls. He topped that mark on March 28, scoring 27 points in a 110–99 win over the Brooklyn Nets.
The Heat finished the regular season as the third seed in the Eastern Conference with a 48–34 record. Whiteside finished as the league's leading shot-blocker in 2015–16, and he earned selection to the NBA All-Defensive Second Team. In the first round of the playoffs, the Heat faced the sixth-seeded Charlotte Hornets, and in a Game 1 win on April 17, Whiteside made his postseason debut with 21 points and 11 rebounds. The Heat went on to lose to the Toronto Raptors in the second round.
On July 7, 2016, Whiteside re-signed with the Heat on a four-year, $98 million contract. In the Heat's season opener on October 26, Whiteside recorded 18 points, 14 rebounds and four blocked shots in a 108–96 win over the Orlando Magic. On October 30, he tied his career high with 27 points and grabbed 15 rebounds in a 106–99 loss to the San Antonio Spurs. With 21 points and 16 rebounds against the Toronto Raptors on November 4, Whiteside recorded his fifth straight double-double, a franchise record streak to open a season. On November 10, he recorded 20 points and 20 rebounds against the Chicago Bulls for his third career 20-20 game. The only player to have more in a Heat uniform is Rony Seikaly, with 12. Five days later, he scored 19 points and grabbed an NBA season-high 25 rebounds in a 93–90 loss to the Atlanta Hawks. On November 21, in a loss to the Philadelphia 76ers, Whiteside set a career high with 32 points while reaching double digits in rebounds for the 13th consecutive game to start the season. On December 14, he recorded 26 points and 22 rebounds in a 95–89 win over the Indiana Pacers, marking his fourth career 20-20 game. Whiteside went on to miss four games in early January with a right retinal contusion. On February 1, 2017, Whiteside grabbed his 2,000th rebound in a 116–93 win over Atlanta; he finished the game 18 points and 18 rebounds. Three days later, he scored 30 points and grabbed 20 rebounds in just 27 minutes in a 125–102 win over the Philadelphia 76ers, extending Miami's winning streak to 10. The 30-20 game was the first of his career, and the ninth in Heat history including playoffs. He joined Bill Laimbeer as the only players in NBA history to post a 30-point, 20-rebound game in no more than 27 minutes—Laimbeer did it in the 1984–85 season. On March 12, he had 26 points and 21 rebounds in a 102–98 loss to Indiana. It was Whiteside's fifth 20/20 game this season. He also tied his career high with 10 offensive rebounds in the game. On March 21, he had a 23-point, 14-rebound performance in a 112–97 win over the Phoenix Suns. He reached 936 rebounds for the season during the game, setting a single-season franchise record by going two above Seikaly's 1991–92 total (934). Whiteside also recorded his 57th double-digit rebound game of the season, a Heat record—one more than Seikaly in 1991–92. On April 2 against Denver, Whiteside became the first Heat player to record 1,000 points and 1,000 rebounds in a season. Whiteside finished the season as the league's leading rebounder.2010 Sporting News second team All-American
2010 Conference USA Defensive Player of the Year
2010 Conference USA Freshman of the Year
2010 Conference USA All-Freshman Team
2010 A member of FOXSports.com's All-Freshman Team
2010 CBSSports.com Freshman All-American Team
2010 Conference USA All-Defensive Team
2010 Conference USA 7-time Rookie of The Week
2010 Second Team All-Conference USA
2010 NCAA Second Team All-Freshman Team
2010 NCAA Division I blocks leader
2010 First NCAA Conference USA player to ever record three triple-doubles in a season
Whiteside is the son of Hasson Arbubakrr and Debbie Whiteside. His father played in the NFL for the Minnesota Vikings and Tampa Bay Buccaneers from 1983 to 1984. Whiteside has a younger brother named Nassan, who has autism. In 2012, Nassan's Place was incorporated in the state of New Jersey as a non-profit organization. Nassan's Place provides low to moderate income families the opportunity to receive quality and affordable care for their children in a safe and carefree environment.