[7][8] Earlier the same day, in the prelims of the same event, he broke his first world junior record of the Championships with a time of 51.23 seconds.

[12] At the 2018 Hungarian Spring National Championships, Milák, who was just 18 years of age, lowered his own world junior record in the 200 metre butterfly to a 1:52.71.

[15] At the 2018 European Aquatics Championships held in Glasgow, Scotland in August, he won the gold medal in the 200 metre butterfly event with a time of 1:52.79.

[18][19] His second gold medal of the Youth Olympic Games came in the 200 metre freestyle where he was the only swimmer under 1:48.00, winning in a time of 1:47.73.

(Lewisville, Budapest) Due to a positive test of having COVID-19, Milák was unable to participate in the 2020 International Swimming League at full capacity, he was on the roster of Team Iron though was out of the season.

[47] Later in the day during the finals session, Milák swam a personal best time in the 100 metre butterfly at 49.92 seconds and won the silver medal in the event behind Tom Shields of the United States.

[50] Starting off day two of competition in the morning, Milák swam a personal best time of 23.34 in the 50 metre backstroke, breaking the Hungarian national record of 23.39 in the event, and advancing to the final ranked first overall.

[51][52] To conclude his morning prelims session, Milák qualified for the final of the 100 metre freestyle ranked sixth overall with his time of 47.48 seconds.

[61] About an hour later, in the prelims of the 200 metre freestyle, he swam within a second of his best time at 1:45.62 and advanced to the final ranked sixth.

[62] Milák just missed the podium in the final of the 50 metre butterfly, finishing fourth with a personal best time of 22.64 seconds.

[69] On 2 November, day one of competition, Milák qualified for the semifinals of the 50 metre backstroke with his time of 23.91 seconds, which was a little over four tenths of a second behind Simone Sabbioni of Italy who competed in the same prelims heat and did not qualify for the semifinals as he was not one of the fastest two swimmers in the prelims heats from his country.

[83] He followed up his morning time with a 47.08 in the evening semifinals, placing ninth and earning the designation of alternate for the final.

[85] Three days later, in the final of the 200 metre butterfly, he lowered his own world record in the event to a 1:50.34 and won the gold medal, finishing 3.03 seconds ahead of the silver medalist Léon Marchand of France.

[86][87][88] Swimming the anchor leg of the 4×200 metre freestyle relay in the final two days later, he split a 1:44.68 to help achieve a time of 7:06.27 and fifth-place finish.

[99] Starting off the evening session, he won the silver medal in the 100 metre freestyle with a Hungarian record time of 47.47 seconds.

[100][102] Day four, Milák ranked first in the morning prelims heats of the 200 metre freestyle, qualifying for the semifinals with a time of 1:46.26.

[104] Starting off the evening session, he won the gold medal in the 100 metre butterfly with a time of 50.33 seconds.

[113][114] He won his third gold medal of the Championships the following day, finishing first in the 200 metre butterfly with a time of 1:52.01, which was 2.77 seconds ahead of silver medalist and fellow Hungarian Richárd Márton.