Hixon was born in Amherst, Massachusetts to Mandy and David Hixon. He has an elder brother Matthew. He studied at Amherst Regional High School. In 2013, he enrolled at the University of Texas in Austin, but moved after a year to Indiana University in Bloomington.
Hixon's mother is a diving coach at the University of Massachusetts and started coaching Michael Hixon diving when he was aged seven. He started entering competitions two years later. He was also involved in other sports – basketball, football and lacrosse, but chose to concentrate on diving. He decided to forego football in the freshman year in high school, and although he also later made the varsity basketball team, scheduling conflicts meant that he had to abandon basketball.
Hixon began diving at the national level when he was 12 and has won the 1-meter competition at the national championships three years running. Hixon is a six-time junior U.S. champion, and won two bronze medals, in the 1 meter and 3 meter events, at the 2009 Junior Pan-American Diving Championships in Calgary.
He subsequently paired with Kristian Ipsen to win a silver at the 2010 FINA World Junior Diving Championships in Tucson, Arizona in the 3 meter synchronized springboard event, but only managed a tenth place finish in the 3 meter solo event.
Hixon won in the 3 meter springboard event at a national selection camp and qualified for Youth Olympic trials in Guadalajara, Mexico, where he won a bronze medal and thus secured a spot to represent the United States at the 2010 Summer Youth Olympics in the 3 meter springboard event.
The event in the first-ever Youth Olympics in Singapore consisted of a 15-man preliminary round and an eight-man final round. After the ten-dive preliminary round, Hixon carried over enough points into the final to begin the final round in third. Although he was sixth after his first dive in the final and fourth heading into his final dive, a poor dive by Italy's Giovanni Tocci allowed Hixon to claim bronze on his final dive, finishing with a score of 554.65 points behind Qiu Bo of China and Oleksandr Bondar of Ukraine.
At the 2011 US National Championships, Hixon captured the senior men 1-meter springboard title at the UCLA's Spieker Aquatics Center in Los Angeles. He also won silver in the 3m synchro with Darian Schmidt at the 2013 AT&T National Diving Championships, and won the 1-meter springboard at the 2016 USA Diving Winter National Championship.
Hixon also won NCAA SWimming and Diving Championships titles on both the 1-meter and 3-meter springboard events in 2014.
Hixon qualified for his first senior international competition, the 2013 World Aquatics Championships in Barcelona, with Troy Dumais, and finished fifth in the men's 3-meter synchronized event.
In the 2015 World Aquatics Championships in Kazan, Russia, Hixon won bronze in the men's 1-meter dive.
Hixon qualified for and represented the United States in both the 3 metre synchronized and men's individual 3 metre springboard events at the 2016 Summer Olympic Games in Rio. He teamed up with Sam Dorman on the 3 metre synchro only after team changes in March 2016, but won the U.S. trials in their first competition together in June 2016.
In the men's 3 meter springboard synchro event, Hixon along with his diving partner Sam Dorman was placed second and won the silver medal with a score of 450.21, behind Jack Laugher and Chris Mears of Great Britain (454.32) but in front of the Chinese pair Qin Kai and Cao Yuan (443.70).
In the mens individual 3 metre springboatd, he finished 10th, while his former 3 metre synchro partner Kristian Ipsen placed fifth in the same event.
Hixon's parents both coach in American collegiate sports. His mother, Mandy Hixon, who is his personal coach, is also the diving coach at the University of Massachusetts Amherst and formerly coached at Amherst College and Williams College. His mother was one of the United States' three coaches at the 2010 FINA Junior World Championships.
His father, Dave Hixon, has been the basketball head coach at Amherst College, since 1977, winning the 2007 NCAA Men's Division III Basketball Tournament.