During UC San Diego's time in NCAA Division II and the California Collegiate Athletic Association starting in the 2000–01 season, UC San Diego placed in the top 5 in the Division II NACDA Directors' Cup standings nine times, including three 2nd-place finishes.

NCSA Athletic Recruiting ranked the Tritons as the nation's top Division II program for eight consecutive years.

After the Big West added the University of Hawaii in 2010, they would have 10 teams, meaning any extra member would require more conference games in basketball, upsetting the current schedule balance.

In addition, in order to meet the minimum Division I scholarship requirements, the student body would need to vote for a fee increase sometime during the 2011–2012 academic year.

[4] In March 2012, the UC San Diego student body rejected an increase in activity fees to support the move to Division I.

In January 2016, Associated Students UC San Diego unanimously approved the wording of a new Division I referendum.

[8] UC San Diego's move remains contingent upon an invitation to join the Big West Conference.

The Tritons' joining the Big West as an affiliate for men's volleyball was not an indicator that the Tritons would be accepted as a full member yet since UC San Diego had long played the sport in the MPSF at a Division I level and was part of the original coalition talks with the Big West to split from MPSF men's volleyball.

However, on November 27, 2017, UC San Diego was accepted and officially started the journey towards the Big West conference along with Cal State Bakersfield.

[10] A member of the Big West Conference, UC San Diego sponsors teams in ten men's, eleven women's, and one coed NCAA sanctioned sports.

From Fall 2000 to Spring 2017, UC San Diego teams competed primarily in the California Collegiate Athletic Association.

The UC San Diego women's basketball team plays its home games at LionTree Arena.

The UC San Diego men's and women's fencing squads compete at Main Gym and RIMAC Arena.

[19] The team hosts the Annual BladeRunner Regional Open Circuit tournament as part of the United States Fencing Association.

[20] The UC San Diego rowing team was established in 1966 and practices on Mission Bay, roughly 10 miles from the main university campus.

On March 26, 2021, UC San Diego and the Colonial Athletic Association jointly announced that the Triton's women's rowing team had joined the conference effective immediately.

Fueled by 2 wins from Junior Katja Pavicevic (200 IM, 200 Breaststroke), as well as individual wins from Julissa Arzave (1650 Freestyle), Ciara Franke (200 Freestyle), and Tina Reuter (400 IM), and multiple relay victories, the Tritons edged out Hawaii by a meager 12.5 points.

The UC San Diego men's volleyball team competes in the Big West Conference, having joined from the Mountain Pacific Sports Federation for the 2018 season (2017–18 school year).

The UC San Diego women's volleyball team plays its home matches at LionTree Arena.

[37] The UC San Diego women's water polo team competes in the Big West Conference against Division I opponents.

UC San Diego has not fielded a football team except in Fall 1968 when a newly formed pigskin organization turned in a winless season and then folded for lack of interest.

[44] Opposition to "big-time" football comes from a wide range of school faculty and administrators such Daniel Wulbert, Revelle College provost, who says that any boost to school spirit would not be worth the sacrifice, and that he wants UC San Diego to "have a life for reasons other than watching hired athletes come and play.

"[45] Both sides acknowledge that adding an 80- to 100-man[46] football team would not only cost some US$1–1.5M annually, but that the initial outlay in equipment and facilities would be in the tens of millions.

[45] The UC San Diego Tritons competed in the NCAA Tournament across 20 active sports (1 co-ed, 9 men's, and 10 women's) 222 times at the Division II level.

[49] Results UC San Diego won 20 national championships at the NCAA Division III level.

UC San Diego had 47 Tritons win NCAA individual championships at the Division II level.