Ogwumike chose Stanford over Baylor, Duke, Connecticut, Tennessee and Notre Dame. She was a member of USA Under 18 Team that won gold in Argentina on July 23–27, 2008. Nneka tallied 20 points and 15 rebounds in the championship game of the Under-18 FIBA Americas. She led team USA to a 5-0 record while leading the team in scoring and rebounding. She was named MVP of this tournament in Argentina.
Nneka has a sister, Chinenye 'Chiney', who is a 6'3" basketball player and attended Stanford with her.
On January 23, 2010, Ogwumike broke the Cardinal record for rebounds in a game with 23 to go along with 30 points in a 100-80 win at Oregon.
On December 20, 2011, Ogwumike scored a career-high 42 points on 19 for 27 shooting while also grabbing 17 rebounds in a 97-80 win over the sixth-ranked Tennessee Lady Vols.
On January 7, 2012, Ogwumike surpassed both the 2,000 point and the 1,000 rebound thresholds for her career with a 33 point, 16 rebound performance against Oregon State.
Ogwumike left the Stanford Cardinal as the second all-time leading scorer for the women's basketball program behind only Candice Wiggins.
Ogwumike was a member of the USA Women's U18 team which won the gold medal at the FIBA Americas Championship in Buenos Aires, Argentina. The event was held in July 2008, when the USA team defeated host Argentina to win the championship. Ogwumike helped the team win all five games, starting all five games and leading all scorers with 12.6 points per game. She was also the leading rebounder with 8 per game. Ogwumike recorded 15 rebounds in the final game against Argentina, an U18 record.
Ogwumike continued on to the USA Women's U19 team which represented the USA in the 2009 U19 World's Championship, held in Bangkok, Thailand in July and August 2009. Although the USA team lost the opening game to Spain, they went on to win their next seven games to earn a rematch against Spain in the finals, and won the game 81–71 to earn the gold medal. Ogwumike started all nine games and was the team's leading scorer, with 13.6 points per game. She was the leading rebounder with almost ten per game, and was named to the all-tournament team.
Ogwumike played on the team presenting the USA at the 2011 World University Games held in Shenzhen, China, along with her sister, Chiney Ogwumike . The team, coached by Bill Fennelly, won all six games to earn the gold medal. Ogwumike averaged 13.2 points and 5.7 rebounds per game, both second place on the team behind Elena Delle Donne.
On April 16, 2012, the LA Sparks picked Ogwumike first overall in the 2012 WNBA Draft. She became the second player from Cypress-Fairbanks High School to be drafted No. 1 overall into the WNBA behind Lindsey Harding in 2007.
On July 12, 2012, Ogwumike set a career-high in rebounds with 20 to go along with 22 points in a 77-74 win over the eventual WNBA champion Indiana Fever. On September 13, 2012, she scored a career high 30 points on 10 of 15 shooting to go along with 11 rebounds in an 86-77 win over the Chicago Sky. In the regular season finale on September 20, 2012, Nneka matched her teammate Candace Parker for team highs in both points and rebounds with each player earning 22 and 11, respectively, in a 92-76 win over the defending WNBA champion Minnesota Lynx. Ogwumike was 10 for 13 from the field.
Ogwumike was named WNBA Rookie of the Month four out of five times in her rookie season. On October 7, 2012, Ogwumike was awarded as the 2012 WNBA Rookie of the Year. It marked the fifth consecutive year that the award had been won by the first overall draft pick.
In PLKK season 2012/13 she played for CCC Polkowice and won Championship's title and Polish Cup as well. With CCC she participated in EuroLeague Women 2012–13 reaching Final Eight and ranked #1 overall in Free Throws Percentage (90.3%).