2016–2019 2016 US Olympic Trials In 2016, Stewart placed 78th in the 200 meter backstroke with a 2:04.74 and 135th in the 100 meter backstroke with a time of 57.57 seconds at the
2016 US Olympic Trials in
Omaha, Nebraska.
2019 World University Games At the
2019 World University Games held at
Piscina Felice Scandone in
Naples,
Italy in July 2019, Stewart placed 8th in the 50 meter butterfly with a time of 24.00 seconds, won the bronze medal in the 100 meter butterfly with a time of 52.11 seconds, and split a 53.85 for the backstroke leg of the 4×100 meter medley relay in the prelims heats and won a gold medal in the event when the finals relay, on which
Justin Ress substituted in for Stewart, finished first in 3:33.02.
2021 2020 US Olympic Trials At the
2020 US Olympic Trials in Omaha, Nebraska, and held in 2021 due to the
COVID-19 pandemic, Stewart placed 10th in the 100 meter backstroke on the second day of competition with a time of 53.91 seconds. In the final of the 100 meter freestyle three days later, Stewart placed eighth with a time of 48.51 seconds. For the final of the 100 meter butterfly two days later, he tied
Trenton Julian for fourth-place with a time of 51.78 seconds.
2021 International Swimming League On August 29, 2021, Stewart broke the
world record in the short course 100 meter backstroke at Piscina Felice Scandone in Naples, Italy as part of regular season competition during the
2021 International Swimming League representing the
Cali Condors. His world record time of 48.33 seconds in the event broke the world record of 48.58 seconds set in 2020 by
Kliment Kolesnikov of
Russia. One day earlier, Stewart broke the
American record in the short course 100 meter backstroke with a time of 48.91 seconds when he swam the first, backstroke, leg of the 4×100 meter medley relay. Come the final match of the 2021 season in December, Stewart set a new
Americas record and American record in the 4×100 meter medley relay with teammates
Nick Fink (breaststroke),
Caeleb Dressel (butterfly), and Justin Ress (freestyle) in a combined relay final time of 3:19.64.
2022 Pro Swim Series – San Antonio Stewart swam a 52.42 in the prelims heats of the 100 meter butterfly at the 2022 Pro Swim Series in
San Antonio, Texas, held at
Northside Swim Center in March and April, qualifying for the final later in the second day of competition ranking second behind
Shaine Casas. In the final he placed third, finishing 0.84 seconds behind first-place finisher Shaine Casas with a time of 51.93 seconds. In the prelims session the following morning, he qualified for the final of 100 meter backstroke with a time of 55.44 seconds and overall second-rank. He placed second in the final, swimming a 54.43 to finish less than a second behind Shaine Casas. He qualified for the b-final of the 100 meter freestyle the following morning, ranking thirteenth overall with a time of 50.06 seconds, in which he went on to swim a 50.39 and finish fifth, thirteenth-place overall. He near-equaled his time from the prelims in the b-final, swimming a 49.35 to finish fourth and place 12th overall. Day two of competition, he qualified for the final of the 50 meter butterfly with an overall rank of sixth and a time of 23.89 seconds in the morning prelims heats. In the final, he swam a time of 23.91 seconds to place seventh. With a time of 52.40 seconds in the 100 meter butterfly preliminary heats on day three, he qualified for the b-final of the event ranking tenth. He did not swim in the event's finals. ==World records==