She has won two Olympic gold medals playing on the United States women's national basketball team in the Tokyo 2020 and the Paris 2024 games.

[7][6] The team that originally denied Collier a chance to try out later offered her a spot, but she remained with the Lady Warriors.

In her sophomore year, she transferred to Incarnate Word Academy,[10] where she averaged a high of 24.6 points and 12 rebounds.

Her family moved to St. Louis after her mother's job in hospital administration called for a transfer to the larger city.

She became the fifth player in the exclusive 2000/1000 club, joining UConn greats Maya Moore, Tina Charles, Breanna Stewart and Rebecca Lobo.

[13] She was a member of the 2016 Connecticut Huskies National Champion team and reached the Final Four in each of her four years at UConn.

She received the Katrina McClain Award for Power Forward of the Year from the Naismith Memorial Basketball Hall of Fame in her senior season.

As a duo, Collier and Katie Lou Samuelson scored the most points in UConn WBB history (4688), topping B. Stewart and M. Jefferson, two teammates from their freshman season.

[14] In her first WNBA game, Collier scored 27 points against the Chicago Sky, the second-highest debut ever for any rookie (after Candace Parker).

[16] Collier is the fourth player (after Maya Moore, Catchings, and Sheryl Swoopes) to have a season with 400 points, 200 rebounds, 75 assists, 50 steals, 25 blocks and 25 made three-pointers.

[15] Collier was voted to the 2019 WNBA All-Rookie Team, and made an All-Star as an injury replacement for A'ja Wilson.

[17] In the 2020 season while in the WNBA bubble, Collier started a podcast with A'ja Wilson, Tea with A & Phee, which was picked up by Just Women's Sports the next year.

She stated she wanted to be able to return to play once more with Sylvia Fowles, who retired from the Lynx and the WNBA after the 2022 season.

[30] She was named the Western Conference Player of the Week for the fifth time on May 21, 2024, averaging "24.5 points on 46.3% shooting, 10.5 rebounds, 2.5 assists, 3.5 steals and 2.0 blocks per game.

[37] She was later named the Western Conference Player of the Month for August 2024, which was the first time Collier received this award.

[38] For the third time in the season, Collier was named the WNBA Western Conference Player of the Week for September 2–8.

[41][42] Collier was the runner up for the WNBA MVP award with 66 out of 67 votes for second place in the shadow of A'ja Wilson's historic season.

[43] When Maya Moore was in Minnesota for her jersey retirement in August 2024, she said of Collier, "I can tell that she's hitting her prime, and the sky's the limit for her.

[49] By the end of the finals, Collier became the first player in the league to lead a single playoff run in points (285), rebounds (107), steals (25), and blocks (23).

[52] In 2023, Collier played for Fenerbahçe in the Turkish Super League on a short term contract, along with her Lynx teammate, Kayla McBride.

[70] Collier is also partnering with Opill, the first over-the-counter birth control pill in the U.S., to promote reproductive rights and sexual health.

[74] Her father, Gamal Collier, explained to the New York Times that he brought up Napheesa to know the "importance of self-sufficiency and responsibility and upholding the family name.