2019 2019 National Championships At the
2019 US National Championships in
Stanford, California, Mitchell ranked highest in the 400 meter freestyle at second place with a time of 3:48.09, and also ranked fifth in the 1500 meter freestyle with a time of 15:11.52, 25th in the 200 meter freestyle with a time of 1:48.92, and 51st in the 400 meter individual medley with a time of 4:29.50.
2019 World Junior Championships In August 2019, Mitchell represented the United States at the
2019 World Junior Championships in
Budapest,
Hungary, winning gold in the 4x200 meter freestyle relay and setting a new
world junior record and
Championships record for the event with his relay teammates. He placed fourth in the 400 meter freestyle with a time of 3:47.95, seventh in the 800 meter freestyle in 7:54.70, and seventh in the 1500 meter freestyle where he finished in 15 minutes, 16.28 seconds. His swims in the 400 meter freestyle and 800 meter freestyle qualified him for the US National team. His time in the 400 meter freestyle was the fastest on record for an American swimmer 17 years of age. His second-place finish, and time trial performance qualified him to
represent the United States at the
2020 Olympic Games.
2020 Summer Olympics At the
2020 Summer Olympics in
Tokyo,
Japan, Mitchell placed 8th with a time of 3:45.39 in the final of the
400 meter freestyle. In the prelims heats, he swam a time of 3:45.38 to qualify for the final ranking seventh, just 0.07 seconds behind sixth-ranked swimmer and teammate
Kieran Smith.
2022 2022 Big Ten Championships Mitchell swam a 1:32.49 for the second leg of the 4×200-yard freestyle relay on the first day of the
2022 Big Ten Conference Championships in February, helping achieve a second-place finish with a final relay time of 6:14.59. The following day, he swam a 4:18.10 in the prelims heats of the 500 yard freestyle to qualify for the final later in the day ranking seventh. He placed second in the final with a time of 4:12.88. For the prelims heats of the 400 yard individual medley on day three, Mitchell ranked fourth with a time of 3:45.92 and qualified for the final. He lowered his time to a 3:41.39 in the final to finish second. The final day of competition, day four, he placed second in the final of the 1650 yard freestyle with a time of 14:44.22. Less than one week later, Mitchell placed second in the 400 meter freestyle at the
Westmont, Illinois stop of the 2022 Pro Swim Series with a time of 3:51.12. The next morning, he qualified for the final of the 200 meter freestyle with a time of 1:50.86, ranking third overall 0.28 seconds behind first-ranked
Patrick Callan. In the final, he placed second in a personal best time of 1:48.63, finishing 0.04 seconds behind first-place finisher
Marwan Elkamash.
2022 NCAA Championships The first day of the
2022 NCAA Championships in late March, Mitchell helped place fourteenth in the 4×200 yard freestyle relay with a split time of 1:34.36 for the second leg of the relay to contribute to the final time of 6:14.56. In the 500 yard freestyle on day two, he placed 46th with a time of 4:21.24. On the third day, he placed 36th in the prelims heats of the 400 yard individual medley with a time of 3:52.73. On December 2, he won the gold medal in the 200 meter freestyle, finishing 0.77 seconds ahead of silver medalist
Zane Grothe with a time of 1:47.38. The following, and final day, he first won the b-final of the 200 meter backstroke with a time of 2:00.75, then tied
Hunter Armstrong in the b-final of the 100 meter freestyle with a personal best time of 50.23 seconds for fifth-place. ==Personal best times==