He has won two gold medals for Israel at the youth level, including at the 2019 FIBA U20 European Championship, where he was named tournament's most valuable player.

[5] Deni Avdija played association football until he entered fourth grade, when his friend and teammate Itamar Vule convinced him to try basketball because of his height.

He was selected to the all-tournament team after leading the event with 24.3 points, 6 assists, and 3.8 steals per game and a Performance Index Rating (PIR) of 31.5.

[10] In February 2019, at the NBA All-Star Weekend in Charlotte, North Carolina, Avdija was named MVP of the Basketball Without Borders Global Camp.

[13] On 19 November, he made his professional debut in the 2017–18 Israeli Basketball Premier League, playing three minutes against Ironi Nes Ziona.

[16] On 24 October 2019, at the age of 18, Avdija made his first start in the EuroLeague, recording six points and three rebounds in 16 minutes in a 76–63 victory over Valencia.

[44] On 6 July 2024, Avdija was traded to the Portland Trail Blazers in exchange for Bub Carrington, Malcolm Brogdon, and several draft selections.

[45] Although he had also been eligible to represent Serbia internationally, due to his father's background, Avdija chose to play for Israel because he had friends there and was more familiar with its language.

Avdija averaged 12.7 points, 6.4 rebounds, 1.1 assists and 1.3 steals per game, while earning a spot on the all-tournament team with teammate Yovel Zoosman.

[52] In July 2019, Avdija led Israel to a second straight gold medal at the FIBA U20 European Championship in Tel Aviv.

He averaged 18.4 points, 8.3 rebounds, 5.3 assists, 2.4 blocks, and 2.1 steals per game, earning MVP and all-tournament team accolades, as the second-youngest player at the event.

[54][55] On 21 February 2019, Avdija made his debut for the Israeli senior national team, in an 81–77 win over Germany, during the 2019 FIBA World Cup qualification stage.

A professional basketball player in Yugoslavia and Israel, Zufer spent 11 years of his playing career with Crvena zvezda and was the team's captain in the 1980s, before moving to the Israeli Premier League in the 1990s and playing 8 seasons for Israeli clubs Ramat HaSharon, Rishon LeZion, Hapoel Tel Aviv, and Elitzur Bat Yam.

[5] Avdija's mother, Sharon Artzi, an Israeli Jew from kibbutz Beit Zera, is a former track and field athlete and basketball player.

[46][62] When he turned 18 years old, he received a deferment from mandatory service in the Israel Defense Forces (IDF) due to his basketball career.

[63] After a series of terrorist attacks in Israel in early 2022, Avdija wrote the Jewish solidarity phrase "Am Yisrael Chai" in Hebrew on his shoes.