For collegiate swimming, Curtiss started competing for North Carolina State University in fall of 2021.

[2][6] For his academic study, Curtiss decided to take Arabic as a foreign language, major in criminology, and minor in psychology.

[11] He competed in three individual events at the 2019 National Championships in Stanford, California in July and August 2019.

[12] At the 2019 World Junior Championships held in August 2019 in Budapest, Hungary, Curtiss competed representing the United States of America.

In the semifinals of the 50-meter freestyle he swam a 21.95, advancing to the final and becoming the third fastest American swimmer in the 17–18 age group for the event behind Caeleb Dressel and Michael Andrew.

[19] On March 3, 2021, at a dual meet, Curtiss swam a 19.26 in the 50-yard freestyle breaking the national independent high school record he set at 19.42 the year before.

[1] Curtiss competed in the 50-meter freestyle at the 2020 USA Swimming Olympic Trials in Omaha, Nebraska, which were postponed to June 2021 due to the COVID-19 pandemic.

[7][30] His swims in the 50-meter freestyle leading up to and at the 2020 Olympic Trials were fast enough to earn him a spot on the 2021—2022 US National Team in the event.

[31][32] Curtiss was one of six current NC State Wolfpack student athletes in swimming to be named to the year's national team.

[36] In the prelims heats of the 50-yard freestyle on day two of the 2022 Atlantic Coast Conference Championships in February 2022, Curtiss swam a personal best time of 18.77 seconds and ranked first heading into the final.

[42] For the prelims heats of the 50-yard freestyle the following morning, he ranked 15th overall with a time of 19.12 seconds and qualified for the b-final in the evening.

[43] Curtiss followed up his NCAA Championships performances by competing at the 2022 Pro Swim Series held at Northside Swim Center in San Antonio, Texas, where he qualified for the final of the 50-meter freestyle on day three with a time of 22.13 seconds in the prelims heats that ranked him first heading into the final.

[52] At the competition, he helped win the first relay at a Duel in the Pool composed of both para-athletes and able-bodied athletes, swimming the anchor leg of the relay, and won the 50-meter freestyle, contributing to a victory for the United States over Australia with a final score of 309-284.

[53][54] Day two of the 2022 U.S. Open Swimming Championships, held in Greensboro, Curtiss ranked first in the morning preliminary heats of the 50-meter freestyle with a time of 22.07 seconds, qualifying for the final.

For his third individual event, the 100-yard freestyle, he tied for sixth-place in the final on day five with a personal best time of 42.44 seconds.

[73][74] Following his individual performance, he swam a 42.09 for the third leg of the 4×100-yard freestyle relay to help win the conference title with a time of 2:47.32.

[73][75] His performances contributed to the NC State Wolfpack winning the men's team overall conference title.

[80] On September 2, 2023 Curtiss took to social media to announce that he was leaving NC State: "Recent life has brought to me some tough decisions, many of which have been very difficult.

NC State has provided me with many positive things, life altering tools that have changed me for the better.

Everything this coaching staff has provided for me was a true blessing, and I thank them for that,” David Curtiss posted on Instagram.