[17] His mother appeared in the British and South African versions of Gladiators, as Laser and Sheena respectively, and his younger sister used to swim.

[27] In August 2015, Andrew made his international debut when he was 16 years old at the 2015 FINA World Junior Swimming Championships in Singapore.

[36][37][12][38] Andrew lowered his National Age Group and world junior records in the final of the 100 meter breaststroke by swimming the race in 59.82 seconds.

[36][39] His time of 1:59.44 in the 200 meter individual medley semifinals tied the world junior record in the event set in 2013 by Gunnar Bentz.

[43] On March 4, 2017, Andrew broke the world junior record in the 200 meter individual medley at the 2017 Arena Pro Swim Series in Indianapolis with his time of 1:59.12 in the final.

[45] In the prelims of the 50 meter freestyle, Andrew broke the world junior record of 22.00, set in the event by Yu Hexin in 2014, with his time of 21.75.

[46] In the final of the 50 meter freestyle, Andrew swam a 21.75 again, tied his world junior record, and won the gold medal in the event.

[47] For the 50 meter backstroke, Andrew broke the world junior record set by Kliment Kolesnikov at 24.94 in 2016 with a time of 24.63 in the prelims.

[49] In the 50 meter butterfly semifinals, Andrew swam a 23.27 and broke the world junior record of 23.39 set by Li Zhuhao in 2015.

[63] He also received press coverage from ESPN who highlighted Andrew's winning four national titles spanning breaststroke, butterfly, and freestyle events.

[3][65][66] As part of the mixed 4x100 meter medley relay with Kathleen Baker (backstroke), Caeleb Dressel (butterfly), and Simone Manuel (freestyle), Andrew won a bronze medal.

[70] In November, Andrew competed at the 2018 Swimming World Cup stop in Beijing, China, tying the American record of 26.15 seconds in the short course 50 meter breaststroke set by Cody Miller.

[83] At the American Final, in College Park, Maryland, he won the 50 meter backstroke, tying with LA Current swimmer Matt Grevers.

[85] Rebounding from his 19th place finish at the 2019 World Championships, Andrew swam a personal best time of 59.14 seconds in the 100 meter breaststroke to win the final at the 2020 TYR Pro Swim Series meet in Des Moines, Iowa in March 2020.

[79] Later in the month, when the 2020 Olympic Games were postponed to 2021 due to the COVID-19 pandemic, Andrew continued training after a six to seven week break from swimming in a pool.

[79][87] One of the ways Andrew adapted to the hiatus in international swimming competition was by experimenting and posting videos of his daily life as a professional swimmer on his YouTube channel.

[95][96][97] He qualified for the 200 meter breaststroke in April 2021 at the TYR Pro Swim Series meet in Mission Viejo where he swam a 2:11.32 in the final of his debut racing the event, which was over three seconds faster than the Wave II trials qualification time.

[96] As part of press coverage leading up to the 2020 Olympic Trials (held in June 2021 due to the COVID-19 pandemic), SwimSwam named Andrew as their top pick in the men's 100 meter breaststroke.

[113] In the morning on day two of the Olympic Trials, Monday June 14, 2021, Andrew swam a 53.66 in the prelims of the 100 meter backstroke, ranking 7th out of all heats.

[114][115] Competing in his first final of the 2020 Olympic Trials in the evening of day two, Andrew swam a 58.73 in the 100 meter breaststroke, ranking #1 for the event.

[128] Andrew also made the top five fastest swimmers all-time globally in the 200 meter individual medley, coming in at number five with his time of 1:55.26.

[137] Andrew filmed some of the typical activities the swimmers took part in during the training camp, edited them together into a vlog format, and shared the video publicly on his YouTube channel to provide viewers a perspective on what it is like to train as a swimmer on the US Olympic team in the time period between qualifying for and competing in an Olympic Games.

[154] He swam a 58.49 for the breaststroke leg of the relay, lowering the split time from the previous world record, a 58.57 by Eric Shanteau in 2009, by eight hundredths of a second.

[161] Andrew remained one of the co-owners of the New York Breakers and decided not to compete as a swimmer in the 2021 International Swimming League season.

[164] On day one of competition, Andrew qualified for the semifinals of the 100 meter breaststroke with a time of 57.54 seconds in the prelims heats, which ranked him eighth.

[176] At the 2022 US International Team Trials in Greensboro, North Carolina, Andrew ranked first in the prelims heats of the 50 meter butterfly on day two with a time of 23.09 seconds and qualified for the evening final.

[185] The first day of swimming competition at the 2022 World Aquatics Championships in Budapest, Hungary in June, Andrew placed ninth in the semifinals of the 100 meter breaststroke with a time of 59.63 seconds.

[8] Legend: h – heats; sf – semifinal; = – tied pre-existing record a with Ryan Murphy (backstroke), Caeleb Dressel (butterfly), Zach Apple (freestyle) a with Olivia Smoliga (backstroke), Kelsi Dahlia (butterfly), Caeleb Dressel (freestyle) Michael Andrew has adopted a unique training style called Ultra Short Race Pace Training.

[202] In the Open Access Journal of Sports Medicine, Nugent et al., 2019 reviewed the science behind the USRPT methodology finding most of the science to be anecdotal in nature, highlighting the training records of Andrew as one form of more concrete scientific evidence, and emphasizing the importance of statistical evidence in proving the effectiveness of the USRPT methodology.

[213] His decision drew attention from national newspaper USA Today who stated Andrew was the biggest name to come out openly about not getting a COVID-19 vaccine in advance of the 2020 Summer Olympics.