[3] For the 2019 Pan American Games in Lima, Peru, Fink was named to the USA Swimming Team in the 200 meter breaststroke.

[15] On the third day of competition, Fink won a silver medal in the 200 meter breaststroke with his time of 2:08.16 and finished less than six tenths of a second behind the gold medalist in the event and fellow American Will Licon.

[16][17] On the fifth and final day of competition, Fink swam the breaststroke leg of the 4×100 meter medley relay in a time of 58.57 seconds, and along with his relay teammates of Daniel Carr (backstroke), Tom Shields (butterfly), and Nathan Adrian (freestyle) won the gold medal in a new Pan American Games record time of 3:30.25.

[18][19] In 2019 he was a member of the inaugural International Swimming League representing the Cali Condors, who finished third place in the final match in Las Vegas, Nevada in December.

[24] In the preliminaries of the 200 meter breaststroke on day four of swimming competition, he finished in a time of 2:08.48 and advanced to the semifinals ranked fourth overall.

[29][30] Fink set a new American record in the short course 50 meter breaststroke with a time of 25.72 seconds at the final match of the 2021 International Swimming League in Eindhoven, Netherlands.

[36] For his performances in the final match, Fink earned 59.5 most valuable player points, ranking second behind Sarah Sjöström of Energy Standard.

[42][43] Fink finished fifth in his heat in the prelims of the 100 meter individual medley in the morning on day three with a time of 52.87 seconds, which qualified him to the semifinals ranking thirteenth.

[44] In his second event of the morning prelims session, the 200 meter breaststroke, Fink qualified for the final ranking seventh with a 2:04.72.

[46] In the final of the 200 meter breaststroke later in the day, Fink won the first world title of his career, winning the gold medal with a time of 2:02.28.

[47][48][49] In the semifinals of the 100 meter individual medley, Fink placed 16th and did not qualify for the final, swimming a time of 54.07 seconds.

[53][54] Later in the same session, Fink set a new American in the 50 meter breaststroke with a 25.68 in the semifinals and qualified for the final ranking second.

[78][79] The next day, he followed up with a silver medal-win in the 200 meter breaststroke, setting an Americas and American record with a time of 2:01.60 in the final to finish 1.25 seconds behind gold medalist Daiya Seto of Japan.

[81] On the final day, he started off by successfully defending his world title in the 50 meter breaststroke with a Championships, Americas, and American record time of 25.38 seconds to earn his second-consecutive title in the event and share the podium with Italians Nicolò Martinenghi (silver medalist) and Simone Cerasuolo (bronze medalist).

[82][83] Concluding competition in the 4×100 meter medley relay, he helped tie the team from Australia for the gold medal in a world record time of 3:18.98, swimming the breaststroke portion in 54.88 seconds.

At the 2024 Summer Olympics, Fink competed in the 100 Breaststroke and tied for second place alongside Adam Peaty of Great Britain, securing himself a silver medal.