Harden beat out four-time MVP LeBron James of the Cleveland Cavaliers and the New Orleans Pelicans' Anthony Davis for the honour, which he had finished as a runner-up for last season to the Oklahoma City Thunder's Russell Westbrook and in 2015 to the Golden State Warriors' Stephen Curry.
Harden is the third player in Rockets history to be named MVP, joining Moses Malone, who won it twice (1979, '82), and Hakeem Olajuwon (1994).
Harden was accompanied by his mother in accepting the award from NBA commissioner Adam Silver.
"I'm not getting emotional, I'm not doing all that, but she's my backbone," Harden said. "Good times, bad times. ... We only get one life and I'm happy she's my mom. I wouldn't have it any other way, for real."
Harden, 28, led the league in scoring last season when he averaged 30.4 points per game. He added 8.8 assists and 5.4 rebounds per game in leading the Rockets to the No. 1 seed in the Western Conference playoffs, where they fell to the eventual champion Warriors in Game 7 of the conference finals.
"Sixth Man of the Year to MVP," said Harden, who claimed the former honour in 2012 as a member of the Thunder. "Shout out to all the youngins' man that got a dream and the vision out there to go take it. Go chase that dream. I'll see you all next year."
Philadelphia 76ers point guard Ben Simmons was named the NBA's Rookie of the Year after the former No. 1 overall pick helped the team break its five-year playoff drought.
Simmons beat out Utah Jazz guard Donovan Mitchell and Boston Celtics forward Jayson Tatum.
"I'd like to thank my family, to start off with," Simmons said. "My family, friends, you know I wouldn't be here without them, and my team-mates of course and my great coach (Brett Brown), and the city of Philadelphia for really embracing me."
Philadelphia 76ers guard Ben Simmons poses for photos following his award for rookie of the year during the NBA Award Show at Barker Hanger.
Image credit: Reuters
Simmons was taken with the top pick in the 2016 NBA Draft, but a broken foot sidelined him for the 2016-17 season.
The 6-foot-10 guard averaged 15.8 points, 8.2 assists, 8.1 rebounds and 1.7 steals over 81 games last season.
Simmons, who turns 22 next month, helped the 76ers advance to the Eastern Conference semifinals, where they lost to the Boston Celtics in a five-game series. He averaged 16.3 points, 9.4 boards, 7.7 assists and 1.7 steals in the playoffs.
Pacers guard Victor Oladipo is the NBA's Most Improved Player after a stellar first season in Indiana that ended in a playoff showdown with James and the Cavaliers.
Oladipo beat out fellow finalists Clint Capela of the Rockets and Spencer Dinwiddie of the Brooklyn Nets.
"Shout out to the Pacers organization for believing in me," said Oladipo, who was dealt to Indiana last offseason in the deal that sent Paul George to the Thunder. "It's only the beginning for us."
Oladipo, 26, averaged a career-high 23.1 points with 5.2 rebounds, 4.3 assists and 2.4 steals to earn his first career All-Star selection, as well as a spot on the All-NBA third team and the All-Defensive first team.
In the playoffs, Oladipo averaged 22.7 points, 8.3 boards, 6.0 assists and 2.4 steals, but it wasn't enough to send the Pacers onto the conference semifinals, as they lost to the Cavaliers in seven games.
Utah Jazz center Rudy Gobert won the NBA's Defensive Player of the Year award, beating out Anthony Davis of the Pelicans and Joel Embiid of the 76ers.
Gobert, who turns 26 on Tuesday, missed 26 games during the regular season with multiple injuries, but still anchored a Jazz defense that posted the second-best defensive rating (101.6) in the NBA last season.
The Frenchman averaged 13.5 points, 10.7 rebounds and 2.3 blocks in 56 games to earn his second straight NBA All-Defensive first-team selection. Gobert led the league in blocks in 2016-17 with 2.6 per game.
Los Angeles Clippers guard Lou Williams is now a two-time NBA Sixth Man of the Year Award winner after being named the league's best bench player for the 2017-18 campaign.Williams, who also won the award with the Toronto Raptors in 2014-15, averaged career highs of 22.6 points and 5.3 assists, along with 1.1 steals in 79 games (19 starts) last season with the Clippers.
"I want to thank the Clippers organization for giving me an opportunity to be myself," Williams said.
He beat out finalists Eric Gordon of the Rockets and Fred VanVleet of the Raptors. Gordon won the award last season.
Dwane Casey earned Coach of the Year honours after guiding the Raptors to a first-place finish in the Eastern Conference.
Casey beat out Boston Celtics coach Brad Stevens and Jazz coach Quin Snyder for the honour.
Under Casey, the Raptors won a franchise-record 59 games opposite 23 losses to claim the No. 1 seed in the East. However, Casey was fired after the Raptors' second consecutive second-round loss to James and the Cavaliers. He was hired as the new coach of the Detroit Pistons, replacing Stan Van Gundy.
Casey also coached the Eastern Conference in this year's All-Star Game.
Daryl Morey of the Rockets earned the NBA's Executive of the Year Award after assembling a team that finished first in the Western Conference.
Under Morey's direction, the Rockets acquired All-Star guard Chris Paul from the Clippers to team up with Harden and rising big man Capela. Houston established a new franchise record for wins with 65 against only 17 losses.
Oscar Robertson was presented with the NBA's 2018 Lifetime Achievement Award.
Before Thunder star Russell Westbrook averaged a triple-double in the past two seasons, Robertson was the most recent player to average a triple-double -- in the 1961-62 season.
A former NBA MVP and 12-time All-Star, Robertson averaged 25.7 points, 9.5 assists and 7.5 rebounds over 14 NBA seasons between the Cincinnati Royals and Milwaukee Bucks.