She played college basketball for the Oregon Ducks and is considered one of the greatest collegiate players of all time.

Ionescu attended Miramonte High School in Orinda, California, where she was named MVP of the McDonald's All-American Game.

As a junior, she led the Ducks to their first Final Four appearance and won the John R. Wooden Award and Wade Trophy as the top player in NCAA Division I.

Her father, Dan Ionescu, escaped communist Romania around the time of the 1989 revolution, seeking political asylum in the United States.

[2] By that time, Dan owned a limousine service in Northern California, where he had chosen to settle because he had several extended family members in that area.

In a 2019 interview with Ava Wallace of The Washington Post, Ionescu admitted to being a "natural scorer", but said that most of the rest of her skill set came from playing alongside both boys and older girls in her childhood:[8]When I was younger, I was always playing with the guys, and I had to find ways to get the ball, because they never wanted to pass to me.

[8] Ionescu was a four-year varsity basketball letter winner at Miramonte High School in Orinda, California under head coach Kelly Sopak.

[10] During her junior year, Ionescu averaged 18.7 points, 7.7 rebounds, 4.2 assists and 4.7 steals per game, and helped Miramonte High School to a 30–2 record with an appearance in the CIF open division semifinals.

She was named the McDonald's All-America game MVP after scoring a record 25 points, including seven three-pointers, with 10 rebounds.

Ionescu finally committed to Oregon just before the school's 2016 summer term began, driving with her father for 8 hours from their Bay Area home to Eugene, making an unannounced visit to Matthew Knight Arena and telling head coach Kelly Graves that she would join the team.

Additionally, she was awarded the USBWA National Freshman of the Year presented by the United States Basketball Writers Association.

[15] Ionescu rose to national prominence in her sophomore year, leading the Ducks to their third regular-season league crown all-time and first-ever No.

[26][27][28] In the 2019 NCAA Tournament, Ionescu led the Ducks to their first Final Four appearance after a 88–84 victory over Mississippi State.

Ionescu won John R. Wooden Award and the Wade Trophy as the best women's college basketball player in NCAA Division I.

[31] This announcement came shortly after Ionescu accepted a place in a newly launched one-year master's degree program in brand creation in Oregon's School of Journalism and Communications.

[32] In the second game of her senior season on November 13, 2019, Ionescu surpassed the 2,000 points, 800 assists mark for her college career with a 109–52 win over Utah State.

[39] Ten days later in the Ducks' 74–66 win at #4 Stanford, she became the first NCAA player ever with 2,000 points, 1,000 assists, and 1,000 rebounds in a career.

Earlier that day, she had been a featured speaker at the memorial service for Kobe Bryant, who had become a close personal friend within the previous two years, flying from Los Angeles to the Bay Area immediately after her speech.

[40] On April 14, 2020, Ionescu was named the winner of the Honda Sports Award as the best collegiate female basketball player in the nation.

According to a 2020 story in the university's web journal Around the O, more than 70 suggestions were provided, but the four top choices were Mariota, Steve Prefontaine, Phil Knight, and Ionescu.

As the story's author Damian Foley put it,Yes, Sabrina Elaine Ionescu, who only earned her diploma in 2019, is considered by UO fans to be one of the four greatest Ducks ever, standing alongside such greats as Marcus Mariota, Steve Prefontaine, and the alumnus who co-founded Nike and made the Phil and Penny Knight Campus for Accelerating Scientific Impact possible.

In her second WNBA game on July 29 against the Dallas Wings, she recorded 33 points, 7 assists, and 7 rebounds in 34 minutes of play.

She scored 26 points, 12 assists, and 10 rebounds, she became the fastest player in WNBA history to record a triple double.

[57] Ionescu signed with Phantom BC, joining her former college teammate, Satou Sabally, and filling the club's final wildcard spot.

[58] On July 14, 2023, Ionescu scored 37 points in the Three-Point Contest, the highest in WNBA history, making 25 of her final 27 shots.

The three-point contest is not a unified record between WNBA and NBA, as the shooting distance and ball sizes are not equal.

[69] In late April 2018, Ionescu and Oregon teammates Erin Boley, Otiona Gildon, and Ruthy Hebard entered the USA Basketball women's national 3x3 championship tournament at the United States Olympic Training Center in Colorado Springs, Colorado.

"[71] She adjusted quickly to the unfamiliar format, leading her team to the championship while going unbeaten and also being named tournament MVP.

[70] Ionescu and her Oregon teammates would be named as the US team for the 2018 3x3 World Cup to be held in June in the Philippines.

[80] On March 10, 2024, Ionescu married NFL center and former University of Oregon football player Hroniss Grasu.