In 2017–18, Badji trained with NBA Academy AfricainSaly, Senegal, where he emerged as one of the best prospects in his age group.[1] By the time he turned 15 years old, he stood about 2.16 m (7 ft 1 in) with a 2.29 m (7 ft 6 in) wingspan.[2] On 27 December 2018, Badji signed with Spanish basketball club FC Barcelona and began playing for its youth sections.[3] In December 2019, he played for U18 FC Barcelona at ANGT Valencia, where he averaged eight points, 8.8 rebounds and five blocks per game.[4]
To prepare for the 2019–20 season, Badji trained with the first team of Barcelona.[5] He spent much of the season playing for FC Barcelona B, the club's reserve team, in the third-tier LEB Plata. On 26 October 2019, Badji had a season-high 12 points, nine rebounds and five blocks in an 86–77 win over Prat.[6] On 18 January 2020, he recorded eight points and a season-high eight blocks in an 88–80 victory over Prat.[7]
After going undrafted in the 2022 NBA draft, on 3 November 2022, Badji was named to the opening night roster for the Wisconsin Herd after signing an Exhibition 10 contract.[9]
On 18 November 2022, the Portland Trail Blazers announced that they had signed Badji to a two-way contract.[10] On 7 March 2023, he underwent surgery on his left knee and was ruled out for at least eight weeks, thus missing out on playing the rest of the season.[11]
On 6 July 2023, Badji signed another two-way contract with the Trail Blazers,[12] but was waived on 24 October.[13] Six days later, he returned to the Herd.[14][15]
On 22 November 2023, Badji signed another two-way contract with the Portland Trail Blazers.[16] On 26 December 2023, Badji made his NBA debut for the Trail Blazers in a 130–113 win over the Sacramento Kings[17] and two days later, he put up 7 points, 9 rebounds, and 3 blocks in 14 minutes of action in a 118–105 loss to the San Antonio Spurs.[18]